CN105855906A - Parallel mechanism with three spatial degrees of freedom - Google Patents

Abstract

The invention discloses a parallel mechanism with three degrees of freedom in space. It includes 3 vertical motion branch chains and a moving platform set in the space surrounded by the 3 motion branch chains; each motion branch chain includes a linear feed system, which drives the moving platform along the vertical Move in a straight direction; the three motion branches are sequentially recorded as motion branch I, motion branch II and motion branch III; motion branch I is connected to the moving platform through a Y-shaped connector; motion branch II is connected through a connecting rod A It is connected with the moving platform; the motion branch chain III is connected with the moving platform through the connecting rod B. The parallel mechanism provided by the present invention has two rotational degrees of freedom and one translational degree of freedom in space, and each branch chain has a simple structure, which effectively guarantees the high dynamic characteristics and force balance characteristics of the mechanism; the rotation of the mechanism in the X and Y directions is free It is a prominent advantage of this mechanism that its terminal moving platform can obtain a higher range of rotation angle and better output accuracy.

Description

A parallel mechanism with three degrees of freedom in space

technical field

The invention relates to a parallel mechanism with three degrees of freedom, in particular to a parallel mechanism with three degrees of freedom in space, and belongs to the field of mechanical manufacturing.

Background technique

The parallel mechanism has compact structure, good modular performance, high stiffness-to-mass ratio, and is easy to realize high-speed movement. The parallel mechanism is a closed-loop system composed of multiple branch chains and dynamic and static platforms, and its degrees of freedom are at most six. A parallel mechanism with less than six degrees of freedom is called a parallel mechanism with few degrees of freedom. Among them, the three-degree-of-freedom parallel mechanism is an important parallel mechanism with few degrees of freedom. In recent years, some hybrid manufacturing equipment based on three-degree-of-freedom parallel mechanisms have been successfully applied in industry, such as the five-axis hybrid machining center Exechoon (W02006054935) based on 2-UPR/SPR mechanisms, and the 3-PRS mechanism-based Ecospeed five-axis hybrid machining center (W02000025976), etc. The hybrid mechanism has the advantages of a large working space of the series mechanism and a compact structure and good dynamic response characteristics of the parallel mechanism. It can realize five-axis high-speed cutting and milling processing in a large working space, and is suitable for the processing of space free-form surface parts.

Patents US6431802 and CN100377847C are currently two common spatial two-rotation-translational parallel mechanisms, respectively 3PRS configuration and 3RPS configuration, both of which have been applied in the field of hybrid machine tools. Both mechanisms include a static platform, a dynamic platform and three branch chains with the same structure and distributed axisymmetrically. The mechanism branch chain involved in US6431802 includes a moving pair, a rotating pair and a spherical joint in sequence; wherein, the moving pair is a driving unit, which cooperates with the static platform through guide rails; the rotating pair and the spherical joint are passive units, and the spherical joint is connected to the corresponding Connecting rod and moving platform. The branch chain of the mechanism involved in CN100377847C successively includes a rotating pair, a moving pair and a ball joint; wherein, the rotating pair is connected with the fixed platform, and the moving pair is a driving unit; the ball joint is a passive unit, which connects the corresponding connecting rod and the moving platform.

In addition, there are many research institutes and scientific research institutions that have constructed a variety of two-rotation-one-shift three-degree-of-freedom parallel mechanisms (such as WO005976, EP1123175, CN102632394, etc.), and universities such as Tsinghua University and Tianjin University have also proposed some parallel spindle head structures. (such as CN101264576, CN101049699, CN101579828, etc.). However, there are relatively few such parallel spindle head structures with a small number of kinematic pairs, a simple structure, and easy control.

Contents of the invention

The purpose of the present invention is to provide a parallel mechanism with three degrees of freedom in space, which can effectively increase the swing angle range of the moving platform and ensure the motion accuracy of the moving platform, and can be connected with the series mechanism to form a five-axis linkage hybrid CNC machining equipment, which overcomes the Disadvantages of the existing parallel spindle head technology.

The parallel mechanism with three degrees of freedom in space provided by the present invention includes three vertically arranged kinematic branch chains and a moving platform arranged in the space surrounded by the three kinematic branch chains;

Each of the kinematic branch chains includes a linear feed system, and the linear feed system drives the moving platform to move vertically;

The three kinematic branches are sequentially recorded as kinematic branch I, kinematic branch II and kinematic branch III;

The motion branch chain I is connected to the moving platform through a Y-shaped connector, and the Y-shaped connector is connected to the motion branch chain I and the moving platform through a rotating pair;

The motion branch chain II is connected to the moving platform through a connecting rod A, one end of the connecting rod A is connected to the motion branch chain II through a rotating pair, and the other end of the connecting rod A is connected to the moving platform. The moving platforms are connected by a universal pair A with two rotational degrees of freedom;

The moving branch chain III is connected to the moving platform through a connecting rod B, one end of the connecting rod B is connected to the moving branch chain III through a spherical hinge, and the other end of the connecting rod B is connected to the moving platform. The platforms are connected by a universal joint B with two rotational degrees of freedom.

In the parallel mechanism, the linear feed system includes a drive device and a linear guide rail;

A slider is connected to the linear guide rail through a moving pair;

The driving device drives the slider to move along the linear guide rail, that is, realizes the freedom of movement of the kinematic branch chain.

In the above-mentioned parallel mechanism, the driving device drives the ball screw to rotate, and drives the slider to move under the action of the rotation of the ball screw.

In the parallel mechanism, the driving device and the linear guide rail are both arranged on a fixed frame.

In the parallel mechanism, the connecting piece is connected with the slider of the kinematic branch chain I;

The connecting rod A is connected with the slider of the kinematic branch chain II;

The connecting rod B is connected with the slider of the connecting branch chain III.

The parallel mechanism provided by the present invention has two rotational degrees of freedom and one translational degree of freedom in space, and each branch chain has a simple structure, which effectively guarantees the high dynamic characteristics and force balance characteristics of the mechanism; the rotation of the mechanism in the X and Y directions is free It is a prominent advantage of this mechanism that the terminal moving platform can obtain a higher range of rotation angle and better output accuracy; on the basis of the parallel mechanism of two rotations and one translation in this space, by adopting the mixed connection with the series platform The form can realize the CNC machining capability of five-axis linkage, so as to realize the efficient and high-precision machining of complex free-form surface parts.

Description of drawings

Fig. 1 is a schematic diagram of the overall structure of the parallel mechanism with three degrees of freedom in space according to the present invention.

Fig. 2 is a schematic diagram of the structure of the kinematic branch III of the parallel mechanism with three degrees of freedom in space according to the present invention.

The marks in the figure are as follows:

10 fixed frame, 11 linear guide rail, 12 ball screw, 13, 18, 21 slider, 14 driving device, 15 Y-type connector, 16 universal joint B with two rotational degrees of freedom, 20 universal joint with two rotational degrees of freedom A, 17 connecting rods B, 19 connecting rods A, 101 motion branch chain I, 102 motion branch chain II, 103 motion branch chain III, 201 moving platform.

detailed description

The present invention will be further described below in conjunction with the accompanying drawings, but the present invention is not limited to the following embodiments.

As shown in Figure 1, the present invention can be used in a schematic diagram of a space two-rotation one-translation parallel mechanism of a five-axis linkage hybrid CNC machine tool, including a fixed frame 10, a moving platform 201 and vertically arranged between the fixed frame 10 and the moving platform 201 according to space The kinematic branch I101, the kinematic branch II102 and the kinematic branch III103. Each motion branch chain has a set of the same linear feed system, which includes a driving device 14, a linear guide rail 11 and a ball screw 12, wherein the driving device 14 and the linear guide rail 11 are fixedly arranged on the fixed frame 10, and the driving device 14 Drive ball screw 12 to rotate.

In the motion branch chain I101, the slider 13 is connected with the linear guide rail 11 by a moving pair, and the slider 13 is driven by the driving device 14 (moving along the linear guide rail 11 under the rotation of the ball screw 12) to input motion for the motion branch chain I101; One end of the Y-shaped connector 15 is connected to the slider 13 through a rotating pair, and the other end is connected to the moving platform 201 through a rotating pair. The directions of the two rotating pairs are shown in FIG. 1 .

In the motion branch chain II 102, the slider 21 is driven by the driving device 14 (moving along the linear guide rail 11 under the rotation of the ball screw 12), which is the input motion for the motion branch chain II 102; one end of the connecting rod A19 passes through the rotating pair and the slider 21, and the other end is connected to the moving platform 201 through a universal joint 20A with two rotational degrees of freedom. The directions of the rotational joint and the universal joint A20 are shown in FIG. 1 .

As shown in Figure 2, in the motion branch chain III 103, the slider 18 is driven by the driving device 14 (moving along the linear guide rail 11 under the rotation of the ball screw 12), and input motion for the motion branch chain III 103; one end of the connecting rod B17 It is connected to the slider 18 through a spherical hinge (not shown in the figure), and the other end is connected to the moving platform 201 through a universal joint B16 with two rotational degrees of freedom. The direction of the universal joint is shown in FIG. 2 .

In the parallel mechanism of the present invention, three moving branch chains are respectively connected with the moving platform 201 and the fixed frame 10 to form a spatial closed-loop mechanism, and the moving platform 201 is driven to move by the input motion of the three sliders. The parallel mechanism of the present invention utilizes the motion branch chain I101, the motion platform 201 and the motion branch chain II102 to jointly realize the rotation degree of freedom of the motion platform 201 around the y-axis direction; the motion branch chain III103 enables the motion platform 201 to have the rotation degree of freedom around the x direction. Since the three kinematic branch chains all have a degree of freedom of movement in the z direction, the moving platform 201 also has a degree of freedom of movement in the z direction. The three branch chains work together to make the mechanism have two rotational degrees of freedom and one translational degree of freedom

In the above-mentioned embodiments of the present invention, the drive device 14 adopts the servo motor-ball screw feeding method, and provides a motion input with a degree of freedom of movement for the slider through the linear guide rail 11. In order to achieve the same purpose, the drive device 14 can also use The linear motor feed method provides a motion input for the slider with one degree of freedom of movement. Certainly, in the specific implementation process, any other driving form that can realize the same motion function is all possible. At the same time, the present invention can adopt a modular design, and can be used in conjunction with two orthogonal serial mobile platforms through the mechanical interface on the fixed frame, thereby forming a five-axis linkage hybrid numerical control processing unit. Wherein, the machine tool spindle and cutting tool can be installed on the moving platform 201 to complete the task of cutting and milling parts.

It should be pointed out that the present invention is proposed for the requirement of three-degree-of-freedom machine tool processing units, but the final application of the present invention is not limited to the field of machine tool processing. Without departing from the essence of the invention, other forms of fixing frame (including shape and layout), driving mode and hinge connection mode and applied in any field shall belong to the protection scope of the present invention.

Claims (5)

1. there is a parallel institution for space three-freedom, including 3 movement branched chain being vertically arranged and be arranged at 3 Moving platform in the space that movement branched chain described in bar is surrounded；

Every described movement branched chain all includes a linear feeding system, and described linear feeding system drives described moving platform edge Vertical direction moves；

Article 3, described movement branched chain is designated as movement branched chain I, movement branched chain II and movement branched chain III successively；

Described movement branched chain I is connected with described moving platform by Y type connector, described Y type connector and described fortune Move and be all connected by revolute pair between side chain I and described moving platform；

Described movement branched chain II is connected with described moving platform by connecting rod A, and one end of described connecting rod A is with described It is connected by revolute pair between movement branched chain II, by two between the other end and the described moving platform of described connecting rod A The universal secondary A of rotational freedom is connected；

Described movement branched chain III is connected with described moving platform by connecting rod B, and one end of described connecting rod B is with described Movement branched chain III is connected by spherical linkage, by two turns between the other end and the described moving platform of described connecting rod B The universal secondary B of the dynamic free degree is connected.

Parallel institution the most according to claim 1, it is characterised in that: described linear feeding system includes driving Device and line slideway；

A slide block is connected by moving sets on described line slideway；

Described driving means drives described slide block to move along described line slideway.

Parallel institution the most according to claim 2, it is characterised in that: described driving means drives described ball Screw turns, drives described slide block to move under the rotary action of described ball-screw.

4. according to the parallel institution described in Claims 2 or 3, it is characterised in that: described driving means and described directly Line guide rail is all located on fixed mount.

5. according to the parallel institution according to any one of claim 2-4, it is characterised in that: described connector is with described The described slide block of movement branched chain I is connected；

Described connecting rod A is connected with the described slide block of described movement branched chain II；

Described connecting rod B is connected with the described described slide block being connected side chain III.