KR100306317B1 - Machine tool equipped with position and posture separation type parallel mechanism - Google Patents

Abstract

The present invention relates to a positional, posture separated driving parallel mechanism for a machine tool, comprising: an upper parallel mechanism composed of a base and a platform, three linear actuators, top and bottom, left and right and front and rear linear motion guides; It consists of a lower parallel mechanism consisting of a base, a platform, a central axis assembly, and three linear actuators, and by adjusting the length of the linear actuator of the upper parallel mechanism, it pushes and pulls the platform equipped with the machining tool in an arbitrary space. The parallel mechanism adjusts the lengths of the three linear actuators in the posture of the platform where the workpiece is fixed, in the io, pitch, and roll directions to determine the posture of the workpiece to process the workpiece.

Description

Machine tool with parallel position-driven parallel mechanism

The present invention relates to a position, posture separation driven parallel mechanism for a machine tool.

In a typical machine tool, as shown in Fig. 1, the platform 2 of the machine tool 1 on which a work piece (not shown) is mounted can make linear movements in the X and Y axis directions, and this X axis And the workpiece can be moved to a desired working position by linear movement in the Y axis direction. The tool 3 is installed on the arm of the vertical column 4, and the workpiece mounted on the platform 2 is moved by the tool 3 by the arm linearly moving in the vertical direction of the Z axis along the vertical column 4. Can be processed. Therefore, in the case where a workpiece having a complex shape is to be processed, several jigs must be combined and the work must be divided. Since the tool 3 is also supported by one link, there has been a problem that the machine structure must be heavy because it has to be strong.

In order to solve the problems of the general machine tool as described above, as shown in Fig. 2, a parallel mechanism provided with six linear actuators capable of simultaneously adjusting position and posture has been proposed in Japanese Patent Laid-Open No. 9-234638.

The conventional parallel mechanism 10 as shown in FIG. 2 has six linear actuators 13 between the base 11 and the platform 12 to obtain arbitrary positions (3 degrees of freedom) and attitudes (3 degrees of freedom). Are provided.

The parallel mechanism 10 is provided with a base 11 at the top as shown in the figure, the platform 12 for supporting the tool is provided at a position away from the bottom of the base 11 by a predetermined distance. The linear actuators 13 have one end connected to the platform 12 via a universal joint and the other end connected to the base 11 via a ball socket joint. The linear actuators 13 can also be individually adjusted in length by the operation of a drive means such as a servo motor.

By adjusting the length of the linear actuators 13, the tool provided on the platform 12 can be changed in position and posture as the platform 12 adjusts the length of the linear actuators 13. Therefore, the tool installed on the platform 12 can properly appropriately pose at the same time to process the workpiece.

However, in the conventional parallel mechanism as described above, since six linear actuators are intensively installed on the platform, the working space of the platform is narrowed by the interference generated between the ball socket joints, so that the attitude working space of the platform is 30 °. It can not have any more, and also the posture work space becomes a smaller angle when the platform is off the center.

In addition, the conventional parallel mechanism as described above has a small installation space of the ball socket joint for supporting the platform, so that linear actuators are vulnerable to torsional load during machining of the workpiece by the tool, Link motion is involved, the motion analysis is complicated.

Accordingly, an object of the present invention is to provide a machine tool having a large working space and rigidity to the torsional load applied to the tool when the workpiece is processed by the tool, while having a simple position analysis and a posture separation driven parallel mechanism. It is.

The object as described above, the housing; An upper platform provided with a tool for machining a workpiece and driven while being horizontal; A lower platform on which the workpiece processed by the tool is mounted; An upper parallel mechanism for changing the position of the upper platform by varying the length of each of the upper linear actuators provided radially to connect the ceiling of the housing and the upper platform; A lower parallel mechanism for changing the attitude of the lower platform by varying the length of each of the lower linear actuators provided radially across the bottom of the housing and the lower platform; And a linear motion guide assembly for guiding the upper platform when the upper platform is moved by the tool positioning means and for supporting a machining load generated when the workpiece is machined by the tool. According to the position, the position separation drive type parallel mechanism can be achieved by a machine tool.

In the above, the upper linear actuators of the upper parallel mechanism have a lower end connected to the upper platform through ball socket joints disposed on the upper platform at equal intervals of 120 °, and upper ends of the housing through universal joints, respectively. It is fixed to the ceiling.

In addition, the lower actuators of the lower parallel mechanism are connected to the lower platform through ball socket joints disposed at the lower platform at equal intervals of 120 °, and the upper ends are fixed to the bottom of the housing through universal joints, respectively. .

The lower platform is pivotally supported by a central shaft assembly provided at the center of the lower linear actuators, the central shaft assembly being spherically coupled to the upper central shaft and the upper central shaft fixed to the lower center of the lower platform. It has a lower central axis fixed to the bottom of the housing.

The linear motion guide assembly includes two pairs of vertical motion guides respectively provided at corner portions of the housing, and a pair of front and rear motion guides installed in the front and rear directions to slide in the vertical direction on the pair of vertical motion guides, respectively. And it is installed so as to slide in the front and rear direction along the front and rear motion guide, and includes a left and right motion guide for guiding the left and right movement of the upper platform.

The left and right motion guide is formed of a rectangular bar to keep the upper platform in a horizontal state.

1 is a view showing a conventional general machine tool,

2 is a view showing a conventional general parallel mechanism.

3 is an overall view of a machine tool with a position, posture driven parallel mechanism in accordance with the present invention;

4 shows a linear motion guide of a machine tool with a positional, posture separated drive parallel mechanism according to the invention.

Fig. 5 shows a lower parallel mechanism of a machine tool with a position, posture separation driven parallel mechanism of the present invention.

<Explanation of symbols for the main parts of the drawings>

20: parallel mechanism 21: housing

30: linear actuator assembly 31: base

32: universal joint 33: linear actuator

34 ball-socket joint 35 upper platform

36: Tool 40: Linear Motion Guide Assembly

41 to 47: linear motion guide 50: lower parallel mechanism

56: central axis assembly

Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the accompanying drawings.

FIG. 3 is a view generally showing a machine tool having a positional, posture separated driving parallel mechanism according to the present invention.

As shown in Fig. 3, the machine tool 20 with a positional, posture driven parallel mechanism according to the invention comprises three linear actuator assemblies for driving the upper platform 35 on which the tool 36 is installed. When the upper platform 35 is driven by the upper parallel mechanism 30, the linear actuators 33, which are composed of 33, the upper platform to guide the upper platform 35 in three directions of X, Y, and Z. Linear motion guide assembly 40 supporting 35, lower platform 51 positioned below the upper platform 35 and mounted thereon with a workpiece (not shown) and oscillatingly driving the lower platform 51. And a lower parallel mechanism with three linear actuators 53 for the purpose.

The upper parallel mechanism is shown in more detail in FIG. 4, and as shown in FIG. 4, the upper parallel mechanism 30 is provided with three linear actuators 33 radially at an angle of 120 ° and a linear actuator ( The upper ends of the 33 are pivotably connected to the base 31 which is fixed to the upper part of the housing 21 (see FIG. 3), respectively, via the universal joints 32, and the lower end of the linear actuator 33 is a three ball socket joint. Spherically coupled to the upper surface of the upper platform 35 through spherical coupling, such as 34, respectively. The lower surface of the upper platform 35 is provided with a tool 36 for machining the workpiece. Each linear actuator 33 can be adjusted in the direction of the arrow by a servo motor or a pneumatic device. Since the length adjustment mechanism of the linear actuator 33 by a servo motor or a pneumatic device is well known, the detailed description is abbreviate | omitted in this specification.

As shown in FIG. 4, the upper platform 35 is slidably installed on the left and right motion guides 47 having a rectangular bar shape, and the left and right motion guides are driven by driving the linear actuators 33 as described above. Move horizontally along the left and right directions. Since the upper platform 35 is installed in the left and right motion guide 47 having a rectangular bar shape, the upper platform 35 only performs horizontal movement in the longitudinal direction of the left and right motion guide 47, and the swinging in the vertical direction is performed. It is constrained by the left and right motion guide 47.

On the other hand, the left and right motion guide 47 is guided in the vertical direction, front and rear by the linear motion guide assembly 40 as shown in Figure 3, the linear motion guide assembly 40 is perpendicular to the corner portion of the housing 21 Up and down movement guides 41, 42, 43, 44 fixed to the upper and lower movement guides (41, 42, 43, 44) to move up and down along the up and down movement guides (41, 42, 43, 44) It includes a pair of front and rear motion guide (45, 46) slidably installed in the). The vertical motion guides 41, 42, 43, 44 and the front and rear motion guides 45 and 46 are formed with straight grooves in the longitudinal direction on the inner surface thereof, and one forward and backward motion guide 45 has a pair of upper and lower sides It is slidably installed in the grooves of the exercise guides 41 and 42, and both side portions of the other forward and backward exercise guides 46 of the other pair of vertical movement guides 43 and 44 in positions facing the one exercise guide 45 are provided. It is slidably installed in the groove.

At this time, the grooves formed on the inner surfaces of the front and rear motion guides 45 and 46 are positioned to face each other, and the left and right motion guide 47 is slidably installed in the grooves of the front and rear motion guides 45 and 46.

Therefore, when a force is applied to the upper platform 35 in the up and down and front and rear directions by the driving of the linear actuators 33, the left and right motion guide 47 along the forward and backward motion guides 45 and 46 is applied to the upper platform 35. While moving forward and backward, the forward and backward motion guides 45 and 46 move upward and downward along the vertical motion guides 41, 42, 43, and 44 by the upward and downward force transmitted through the left and right motion guides 47. do.

As a result, the upper platform 35 on which the tool 36 is installed can move in the X, Y, and Z directions, and can be moved to a position for processing the workpiece installed on the lower platform 51.

Referring to FIGS. 3 and 4, the linear motion guide assembly 40 has the upper platform 35 in the left, right, front, and up and down directions by the linear motion guides 41, 42, 43, 44, 45, 46, 47. By being moved, when the workpiece is machined by the tool 36 located on the upper platform 35, the processing load, in particular the torsional load, exerted on the upper platform 35 via the tool 36 is a linear motion guide. Supported by (41, 42, 43, 44, 45, 46, 47), the processing load on the linear actuator assembly 30 is reduced, thereby preventing the linear actuator assembly 30 from twisting due to the processing load. .

As described above, the linear actuator assembly 30 changes the length of the linear actuators 33 as the three linear actuators 33 linearly move by driving of a servo motor or a pneumatic device, respectively. That is, the three linear actuators 33 are properly synchronized with each other so that the upper platform 35 is properly positioned at the machining position by pushing and pulling the platform 35. At this time, the upper platform by means of the linear motion guides 41, 42, 43, 44, 45, 46, 47 of the linear motion guide assembly 40 such that the upper platform 35 does not have a degree of freedom (no play). The movement of 35 is constrained with three degrees of freedom. The movement of all rotary joints of the linear actuator 33 as well as the restraint movement of the upper platform 35 is determined by the length of the linear actuator 33 and the geometric constraints of the upper parallel mechanism in indirect drive.

The direct drive variable of the mechanism of the invention is the length of the three linear actuators 33, which is made possible by the driving of a servo motor or a pneumatic device using a ball screw.

As described above, once the workpiece machining position of the upper platform 35 is determined, the parameters of the linear motion guide assembly 40 for constraining the movement of the upper platform 35 are immediately determined and the position of the upper platform 35 is determined. According to this, the lengths of the respective linear actuators 33 are calculated. This is a variable that can be directly driven, and is driven by a servo motor or a pneumatic device. At this time, a linear scale sensor may be installed on the vertical motion guides in the vertical direction, the horizontal direction, the horizontal direction, and the horizontal direction.

5 is a schematic illustration of the lower parallel mechanism 50 according to the invention.

If the upper parallel mechanism 30 as described above relates to the position of the tool 36, the lower parallel mechanism 50 relates to the attitude of the workpiece to be processed by the tool 36.

Lower parallel mechanism 50 includes a lower platform 51 on which a workpiece is mounted, the lower platform 51 being positioned below the upper platform 35. The lower platform 51 is provided with three ball-socket joints 52 disposed radially at an angle of 120 ° on its lower surface, and each ball-socket joint 52 is formed by a servo motor or a pneumatic device. The upper end of the linear actuator 53 of variable length is connected. The linear actuator 53 is installed at the lower base 55 where the lower ends are respectively fixed to the bottom of the housing 21 through the universal joint 54.

Also provided in the center of the lower platform 51 is a central shaft assembly 56 in which the upper and lower portions 56a and 56b are connected to each other by spherical coupling, such as ball-socket joints 57. The upper central axis 56a is fixed to the lower center of the lower platform 56, and the lower central axis 56b is fixed to the base 55 at a position corresponding to the upper central axis 56a.

Since the linear actuators 53 are variable in length by a servo motor or a pneumatic device, the lower platform 51 obtains the yaw, pitch, and roll posture of the workpiece, and at this time, the lower platform 51 supporting the workpiece is Support the central shaft assembly 56. On the other hand, by installing a rotary encoder in each movement direction of the lower platform 51 can also directly measure the posture of the workpiece.

In addition, in the lower parallel mechanism 50, the motion of the rotary joint of the lower parallel mechanism 50 is indirectly driven, as in the upper parallel mechanism 30, to the length of the linear actuator and the geometric constraints of the lower parallel mechanism 50. Is determined by.

As described above, the machining platform of the workpiece is taken by the three linear actuators 53 on the lower platform 51 on which the workpiece to be machined is mounted, and the tool 36 located at the machining position of the workpiece processes the workpiece. .

A machine tool having a positional, posture separated driving parallel mechanism according to the present invention configured as described above has the following unique effects.

The combination of each position and posture parallel mechanism allows 6-degrees of freedom, allowing complex machining, and in addition to the respective position and posture parallel mechanisms, the motion of the platform can be controlled by linear motion guides and ball-socket joints. By being constrained, the position and attitude control is possible and the structural analysis is easy, while the torsional load applied to the tool is supported in a large space by the linear motion guide, so that the machining load is distributed to the linear actuator, thereby improving the rigidity of the machine tool. .

Therefore, it is possible to manufacture high rigidity machine tool with small size and light weight, so it is possible to reduce the weight. The linear motion guide is limited to the motion, and the processing load except torsion is supported by the parallel mechanism, so it can be configured as small size.

Although the present invention has been described in detail with reference to the accompanying drawings, it should be understood that the present invention is not limited thereto and various changes and modifications can be made without departing from the spirit of the present invention.

Claims (6)

A housing; An upper platform provided with a tool for machining a workpiece and driven while being horizontal; A lower platform on which the workpiece processed by the tool is mounted; An upper parallel mechanism for changing the position of the upper platform by varying the length of each of the upper linear actuators provided radially to connect the ceiling of the housing and the upper platform; A lower parallel mechanism for changing the attitude of the lower platform by varying the length of each of the lower linear actuators provided radially across the bottom of the housing and the lower platform; A linear motion guide assembly for guiding the upper platform when the upper platform is moved by the tool positioning means and for supporting a machining load generated when the workpiece is machined by the tool. Machine tool with separate driven parallel mechanism. The upper linear actuators of the upper parallel mechanism are connected to the upper platform through ball socket joints arranged on the upper platform at equal intervals of 120 °, and the upper ends of the upper parallel actuators to the universal joint, respectively. And a position, posture separation driven parallel mechanism, which is fixed to the ceiling of the housing. The lower linear actuators of the lower parallel mechanism are connected to the lower platform through ball socket joints disposed at the lower platform at equal intervals of 120 °, and the upper ends of the lower parallel actuators respectively through universal joints. A machine tool having a positional, posture separated driving parallel mechanism, which is fixed to the bottom of the machine. 4. The upper central shaft of claim 1 or 3, wherein the lower platform is supported by a rocking motion by a central shaft assembly provided at the center of the lower linear actuators, and the central shaft assembly is fixed to the lower center of the lower platform. And a lower central shaft that is spherically coupled to the upper central shaft and is fixed to the bottom of the housing. The linear motion guide assembly of claim 1, wherein the linear motion guide assembly is installed in the front-rear direction so as to slide in the vertical direction to the two pairs of vertical motion guides respectively provided at the corner portions of the housing and the pair of vertical motion guides. Position and posture separation drive, characterized in that it comprises a pair of front and rear movement guides, and the left and right movement guides which are installed to slide in the front and rear directions along the front and rear movement guides, and guide the left and right movements of the upper platform. Machine tool with type parallel mechanism. 6. The machine tool according to claim 5, wherein the left and right motion guides are formed of rectangular bars to keep the upper platform in a horizontal state.