CN1246400A - Ganty slide block type machine tool structure with virtal shaft driven by internal and external sets - Google Patents

Abstract

The invention belongs to the technical field of mechanical manufacturing. It includes two vertically installed guide rails, two controllable sliders, two linear drive units that drive the sliders to move in the guide rails, two fixed-length drive rods, a moving platform for installing cutting tools, and a workbench for installing workpieces. One end of two fixed-length driving rods is connected together by a hinge, and the other end is connected with a slider; a driven slider and a telescopic shaft connected thereto are also included. The invention has the advantages of low manufacturing cost, simple structure, good processing manufacturability, flexible tool operation, high precision, fast feed speed, preferential processing direction, multiple functions, good thermal influence calibration and the like.

Description

The structure of virtual axis machine tool with hybrid drive of gantry slider type internal and external pairs

The invention belongs to the technical field of mechanical manufacturing, in particular to a structural design of a virtual axis machine tool with comprehensive functions and a combination of internal and external auxiliary drives.

In the field of mechanical manufacturing, traditional mechanical structures, such as cutting machine tools, have fixed guide rails, and their basic movement mode is to make the tool or workpiece move along the fixed guide rails. This pattern of movement, common to traditional devices, brings with it a number of inherent drawbacks:

First, the traditional machine tools must have high-rigidity bulky and heavy bed, columns and other supporting components and high-precision rail systems fixed to the supporting components, resulting in heavy weight, high price, and difficulty in moving the machine tool.

Second, the cutting tool can only realize the machining feed movement along the given direction of the fixed guide rail, which limits the flexibility of the tool operation. The serial mechanical mechanism design makes the spatial movement need to be realized by the mutual superposition of movements in each direction. It is easy to generate error accumulation and reduce the terminal accuracy.

Faced with the increasingly complex machining shapes and special machining requirements of machined parts, the machine tool industry at home and abroad has adopted various corresponding countermeasures. For example, traditional machine tools meet the requirements of modern processing objects with more complex and bulky structures and expensive fixtures. As a result, the manufacturing cycle is long, the cost is high and the manufacturing quality is difficult to guarantee. In recent years, a new type of machine tool called a virtual axis machine tool has emerged. It uses a telescopic axis or sliding axis that can be controlled in parallel to replace the traditional fixed rail system; it uses a frame structure to replace the traditional bed, column, etc. Bulky components.

The control system of traditional CNC machine tools is based on the Cartesian coordinate system, that is, the three degrees of freedom of movement of X, Y, and Z and the three degrees of freedom of rotation of A, B, and C. The movement of each guide rail system corresponds to one of the degrees of freedom . The controller of the virtual axis machine tool is for each controllable axis. For a certain spatial posture requirement of the tool, there is a corresponding telescopic axis length or sliding axis slider position corresponding to it. That is to say, the virtual axis machine tool realizes the processing requirements through the length of the telescopic axis or the position of the sliding block of the sliding axis. The tool pose described by the Cartesian coordinate system becomes the description of the virtual axis system for the machine tool, while the length of the telescopic axis or the position of the slider of the sliding axis is its actual control axis, so it is called a virtual axis machine tool. This type of machine tool provides a brand-new processing equipment, which fundamentally changes the relative movement mode of the tool and the workpiece, increases the flexibility of the tool operation movement, and makes the equipment have greater processing flexibility and control maneuverability.

The typical structure of the existing virtual axis machine tools at home and abroad mainly includes two types: one is the telescopic axis type internal auxiliary drive virtual axis machine tool, this type of machine tool adopts a frame support structure, and one end of the controllable telescopic axis is connected to the top or bottom of the frame. The other end of the controllable telescopic shaft is connected with the moving platform used for the spindle on which the tool is installed. Due to the frame support structure, this type of machine tool has lighter overall weight and greater processing rigidity under the same processing capacity as traditional machine tools. However, the drive axes of this type of machine are coupled to each other and there is no preferred machining direction. At the same time, the length of each telescopic axis changes all the time, so it is not easy to calibrate the thermal influence. Most of the mechanical structures are special parts, and the degree of standardization is not strong.

The other is a slider-type external auxiliary drive virtual axis machine tool. This type of machine tool also uses a frame support structure. However, the length of each controllable shaft is fixed, and one end of the controllable shaft is connected with the slider to allow the slider to move on the guide rail, and the other end of the controllable shaft is connected with the moving platform on which the spindle motor is installed. This type of machine tool not only has the main advantages of the first type of machine tool, but also effectively avoids the thermal effect of the telescopic leg mechanism of the internal auxiliary drive machine tool due to the use of fixed-size rods, greatly reduces the thermal error in the processing process, and greatly improves the degree of practicality. In addition, through further theoretical analysis and optimized design, the machine tool with this configuration can produce an advantageous motion direction, which is decoupled from other motion directions, and is suitable for the processing of long and complex curved workpieces. Advantages of the structure. The flexibility of tool operation in the dominant movement direction of this type of machine tool is significantly different from that in other processing directions. Although this feature is suitable for processing long and complex curved surface workpieces, it is not as good as other types of workpieces. Machine tools of the first type have advantages.

The purpose of the present invention is to overcome the deficiencies of the prior art, learn from the advantages of the above-mentioned first and second types of virtual axis machine tools, organically integrate the slider drive structure and the telescopic rod drive structure, and design a machine tool with cutting , grinding, transfer, assembly, energy beam processing, head change measurement and other functions of the virtual axis machine tool structure, so that it has a simpler structure, better processing technology, better tool operation flexibility, and more High precision, faster feed rate, preferential processing direction, convenient thermal influence calibration on fixed legs, etc. advantages. Moreover, the manufacturing cost of the machine tool can be reduced and the needs of users for the 3-5 axis linkage numerical control machine tool can be met.

A gantry slider type internal and external auxiliary hybrid drive virtual axis machine tool structure designed by the present invention includes 2 vertically installed guide rails, 2 controllable sliders installed in the guide rails, and 2 straight lines for driving the sliders to move in the guide rails Drive unit, 2 fixed-length driving rods, 1 moving platform for installing cutting tools, and 1 workbench for installing workpieces, characterized in that one end of the two fixed-length driving rods is hinged together, and the other ends It is connected with said one slider; it also includes a driven slider installed in one of the guide rails, a controllable telescopic shaft, said driven slider and said one controllable slider Blocks are fixed together according to the set distance, the driven slider is fixed to one end of the controllable telescopic shaft, the other end of the controllable telescopic shaft is connected to one end of the moving platform, and the other end of the moving platform is connected to the moving platform. Two fixed-length planar connection frames are connected at hinge points to form a parallel closed-chain structure, and the said workbench is independent from the parallel closed-chain structure in terms of driving.

The drive of the machine tool of the present invention is a mixed drive of internal and external pairs, wherein the drive of the two fixed-length drive rods is the drive of the outer pair, and the drive of the controllable telescopic shaft is the drive of the inner pair.

The installation position of the driven slider of the controllable telescopic shaft can be located above, below or at the same position as the controllable slider of the same guide rail. In addition, the connection position of the controllable telescopic shaft and the driven slider can deviate from the guide rail by a certain distance, so as to be suitable for different usage occasions.

The moving platform can be added with a rotation function, and the two fixed-length driving rods can be replaced by a plane frame or a plane plate to increase the rigidity of the machine tool.

Said workbench can be a rotatable and translational workbench made up of a slide table, a motor, a guide rail, and a turntable.

The controllable telescopic shaft can be composed of a cylindrical shell with one end open, a servo motor installed in the shell in turn, a hollow linear guide rod, a ball screw and a ball nut driven by the motor inserted into the guide rod, and the linear guide rod and the ball nut. It consists of a coupling held together by a ball nut.

One of the characteristics of the present invention is that: one end of the moving platform is hinged to a vertex of a triangle formed by two fixed-length driving rods, and the other end is hinged to a controllable telescopic shaft to form a parallel closed-chain structure, so that the moving platform can obtain a high stiffness. In addition to the inherent stability of the triangle, the rigidity of the apex position is also very high, thus effectively ensuring the machining accuracy of the machine tool. In addition, the determination of the vertex of the triangle is only related to the position of the slider, and has nothing to do with the length of the controllable telescopic axis that controls the corner of the braking platform. Since the sliding of the slider is directly reflected in the change of the position of the hinge point, it is easy to realize the position control of this point and obtain good speed and acceleration characteristics of this point.

The second feature is that the two active sliders of the mechanism are respectively installed on the two guide rails, and the sliding direction of the sliders is the priority direction of processing, which is especially suitable for processing some special workpieces. In addition, after the positions of the hinge points of the two fixed-length drive rods are determined, if the interference and limit positions are not considered, the posture of the moving platform at a specific point in the plane is only related to the length of the controllable telescopic axis connected to it, and not to the The exact position of the slider is not directly related. Through further analysis and optimization, the posture of the moving platform and the position of the slider can be decoupled, so that the moving platform can obtain a good ability to realize the posture.

The third feature is that the two fixed-length drive rods are driven by slide blocks connected thereto, also known as external auxiliary drives. It can be seen that the length direction of the two fixed-length driving rods is easy to perform thermal impact calibration. The rotation of the moving platform is driven by the controllable telescopic shaft, which is called the inner pair drive, which effectively improves the turning ability of the moving platform. The two are combined into an internal and external auxiliary hybrid drive mode.

The fourth feature is that the two fixed-length driving rods are connected with the two active sliders by a single hinge, and the single hinge is easy to manufacture, so the processing precision is very high, thereby ensuring the hinge precision of the mechanism.

The fifth feature is that the parallel closed-chain mechanism is a planar mechanism, including two degrees of freedom for translation in the plane and one degree of freedom for rotation around the plane normal. Due to the simple structure, it is possible to carry out in-depth theoretical analysis on the mechanism, obtain the optimal design parameters, and provide conditions for the real-time control of the mechanism. By adding a rotation or a translation perpendicular to the guide rail of the parallel closed-chain mechanism on the platform where the workpiece is installed, it becomes a four or five degrees of freedom machine tool. In addition, a rotation function can be added to the side where the motor is installed on the moving platform, making it a six-degree-of-freedom machine tool, which is suitable for the processing requirements of most complex workpieces.

The sixth feature is that if the parallelogram is formed by the moving platform, the controllable telescopic shaft, a certain length of the driving rod and the vertical guide rail, the controllable telescopic shaft will remain unchanged when the mechanism moves in translation, ensuring that the mechanism will be higher in translation. precision and controllability.

The seventh feature is that the two fixed-length driving rods can be replaced by plane frames or plane plates to increase the rigidity of the machine tool. The moving platform adopts a curved plate structure to facilitate the installation of the spindle motor or other equipment.

The eighth feature is that the movement of the controllable telescopic shaft connected with the moving platform is also completed by the ball screw pair and the servo motor. The controllable telescopic shaft consists of a cylindrical shell with one end open, a servo motor installed in the shell, a hollow linear guide rod, a ball screw and a ball nut driven by the motor inserted into the guide rod, and the linear guide rod and ball nut are fixed. It is composed of joint connectors; one end of the linear guide rod protrudes from the shell to be hinged with the moving platform, and the closed end of the shell is hinged with the driven slider.

The ninth feature is that the installation position of the driven slider connected to the controllable telescopic shaft can be located above, below or at the same position as the adjacent driving slider. In addition, the connection position of the controllable telescopic shaft and the driven slider can deviate from the guide rail by a certain distance, so as to be suitable for different usage occasions.

In summary, the main features of the present invention are reflected in the plane parallel closed-chain structure, the layout of double guide rails and double sliders, the triangular translation structure composed of 2 fixed-length drive rods and sliders, the moving platform and 2 fixed-length drives The connection between the rod and the telescopic shaft, the installation method of the internal and external hybrid drive and the slider, the fixed-length drive rod can be replaced by a plane frame structure, the translation and rotation device of the worktable, and a rotation device is added to the moving platform, which can be controlled There are ten aspects such as the structure of the telescopic shaft, the different installation positions of the driven slider and the different installation positions of the controllable telescopic shaft.

Brief description of the drawings:

FIG. 1 is a schematic diagram of an overall structure of an embodiment of the present invention.

Fig. 2 is a schematic structural diagram of the controllable telescopic shaft of this embodiment.

Fig. 3 is a schematic diagram of the overall structure of Embodiment 2 of the present invention.

Fig. 4 is a schematic diagram of the overall structure of Embodiment 3 of the present invention.

Fig. 5 is a schematic diagram of the overall structure of Embodiment 4 of the present invention.

The structure and working principle of the embodiment of the four gantry slider type internal and external hybrid driving virtual axis machine tools of the present invention will be described in detail below in conjunction with the accompanying drawings.

Embodiment 1 The overall structure is shown in Figure 1. This embodiment consists of fixed-length drive rods 4, 15, controllable telescopic shaft 7, moving platform 8, sliders 3, 6, 16, and guide rails 2, 17 to form a plane parallel closed chain structure. When the moving platform 8 is subjected to force in any direction, each bar of the parallel closed-chain structure is only subjected to tension and compression without bending moment, so it has high rigidity. Due to the frame structure, the weight of the whole structure is also very light.

The active slider 3 slides on the vertical guide rail 2, and the active slider 16 slides on the vertical guide rail 17, forming a dual guide rail and double slider layout. Since the shortest distance between the two active sliders 3 and 16 is the distance between the two guide rails, it is avoided. The branch chain interference situation that is easily produced by the layout of single guide rail and double sliders is eliminated. In addition, the moving platform 8 is located between the two guide rails 2, 17, and the force of the moving platform is more evenly distributed on the fixed-length driving rods 4, 15, thereby further improving the rigidity of the mechanism.

The fixed-length driving rods 4, 15 and the controllable sliders 3, 16 that are hinged to form a triangular translation structure. Due to the inherent stability of the triangle, the vertices, that is, the hinged joints of the fixed-length driving rods 4 and 15 point, with good rigidity. When the controllable sliders 3, 16 change positions, the hinge points of the planar connection frames 4, 15 also change accordingly, and the change of the hinge point positions has nothing to do with the controllable telescopic shaft 7 that controls the rotation angle of the braking platform 8. The changes of the position, speed and acceleration of the hinge point are only relevant to the controllable slide blocks 3,16.

One end of the moving platform 8 is hinged to the controllable telescopic shaft 7, and the other end is hinged to the hinge points of the planar connection frames 4, 15. This design makes the moving platform not only have the advantages of telescopic shaft telescopic control, but also have the fixed-length rod sliding Advantages of control. The good ability of the moving platform 8 to realize attitude and the accuracy of positioning are guaranteed.

The fixed-length driving rod 4,15 slides on the vertical guide rails 2,17 by the slide block 3,16 to change the position and posture, and then drives the change of the position of the moving platform 8, which is the external auxiliary drive. The controllable telescopic shaft 7 controls the change of the attitude of the braking platform 8 through axial telescopic movement, and is driven by the inner pair.

The linear drive units 1, 18 respectively drive the sliders 3, 16 to slide on the vertical guide rails 2, 17, and the driven slider 6 is fixed by the connecting plate 5 and the slider 3, and also slides on the guide rail 2. It can be seen that the sliding direction of the slider is the dominant motion direction of the machine tool, which is fully decoupled from other motion directions, and has the advantages similar to the structure of the traditional Cartesian coordinate system machine tool. The sliding of the sliders 3, 16 causes changes in the posture of the plane connecting frames 4, 15 hinged thereto. Because it is an external auxiliary drive, convenient thermal calibration in the length direction can be performed on the fixed-length drive rods 4 and 15 .

The fixed-length drive rods 4, 15 can be replaced by plane frames or plane plates to increase the rigidity of the machine tool. And moving platform 8 adopts the bent plate structure, and a side of bent plate links to each other with the hinge point of telescoping shaft and fixed-length driving rod 4,15, and the other side can install main shaft motor 9 or other equipment conveniently. In addition, a rotation function can be added to the side where the spindle motor 9 is installed, which expands the processing range and processing flexibility of the machine tool.

The workbench with moving and rotating functions is made up of slide table 12, motor 10, guide rail 11, and rotating workbench 13. The motor 10 drives the workbench 13 and its upper workpiece 14 to rotate, while the sliding table 12 slides horizontally on the guide rail 11, and its motion direction is perpendicular to the horizontal guide rail motion direction of the parallel closed chain structure, effectively expanding the processing range of the machine tool. Although the drive of the moving or rotating table is independent of the parallel closed-chain structure, it effectively expands the processing range and adaptability of the machine tool.

As shown in Figure 2, it is the structure diagram of the controllable telescopic shaft 7 of the present embodiment, among the figure, 27 is a servomotor, can drive the ball screw 21 that is installed on the bearing 26 to make rotational movement according to the requirement, bearing 26 and The servo motors 27 are all installed in the casing 25 . The linear guide bush 20 is fixed on the outer wall 24 , and the outer wall 24 is fixed on the box body 25 , so there is no relative movement between the linear guide bush 20 and the outer wall 24 of the box body 25 . Under the constraints of the linear guide sleeve 20, the linear guide rod 19 can only move linearly in the axial direction and cannot rotate around the axis. The coupler 22 fixes the linear guide rod 19 and the ball nut 23 together, so the ball nut 23 cannot rotate around the axis. When the ball screw 21 rotates, the linear guide rod 19 is driven by the ball nut 23 to perform telescopic movement in the axial direction.

In this embodiment, the two fixed-length driving rods 4 and 15 are both 1100mm, the telescopic range of the controllable telescopic shaft 7 is limited to 845.9mm-1309.8mm, the height of the moving platform 8 is 500mm, and the sliders 3, 6 and 16 are on the guide rail. 2. The slidable distance on 17 is 1500mm, the distance between the two guide rails 2 and 17 is 1000mm, and when the height of the connecting plate 5 connecting the slider 3 and the slider 6 is 500mm, the horizontal direction of the moving platform 8 can be obtained The movable range is 1000mm. When the rotation range of the center point where the motor is installed on the moving platform 8 is required to be greater than ±30°, the horizontal movable range of the moving platform 8 is 500mm.

When the sliding distance of the sliding table 12 of the workbench on the guide rail 11 is 1000mm, the reachable area of the center point where the motor is installed on the moving platform 8 is approximately 1000 ^* 1000 ^* 1000mm ³ (X ^* Y ^* Z). When the rotation range of the moving platform 8 is required to be greater than ±30°, the reachable area is approximately 500 ^* 1000 ^* 1000mm ³ (X ^* Y ^* Z). Wherein X refers to the movable range of the moving platform 8 in the horizontal direction. Y refers to the sliding distance of the slide table 12 on the guide rail 11 , and Z refers to the movable range of the moving platform 8 in the vertical direction.

The structures of embodiment two, three and four are shown in Fig. 3, Fig. 4 and Fig. 5 respectively. It improves the flexibility and diversity of the structure, making it suitable for different occasions. The differences are described in detail as follows;

The driven slider 6 of the second embodiment is installed on the driving slider 3; the driven slider 6 of the third embodiment is installed on the same part of the driving slider 3; and the fourth embodiment is the controllable telescopic shaft and The connection position of the driven slider deviates from the guide rail by a certain distance, and the allowable rotation angle of the movable platform 8 with this structure is significantly increased, which is beneficial to practical engineering applications.

The present invention has the following effects:

First, one end of the moving platform is hinged to a vertex of a triangle formed by two fixed-length driving rods, and the other end is hinged to a controllable telescopic shaft to form a parallel closed-chain structure. Each rod in the structure is only subjected to tension and compression, not torsion, which reduces the machining error caused by the force deformation of the machine tool and ensures the high rigidity of the machine tool. Secondly, the structure uses a plane frame as a supporting rod, which also effectively improves The rigidity of the mechanism is improved, and the inherent stability of the triangle, the rigidity of the apex position is also very high, and finally the rigidity of the machine tool is greatly improved. In addition, the determination of the vertex of the triangle is only related to the position of the slider, and has nothing to do with the length of the controllable telescopic axis that controls the corner of the braking platform. Since the sliding of the slider is directly reflected in the change of the position of the hinge point, it is easy to realize the position control of this point and obtain good speed and acceleration characteristics of this point.

Second, the installation method of the mechanism slider ensures that the sliding direction is the priority direction of processing, which is especially suitable for processing some special workpieces. In addition, after the position of the hinge point of the fixed-length rod is determined, if the interference and limit position are not considered, the posture of the moving platform at a specific point in the plane is only related to the length of the controllable telescopic axis connected to it, but not to the length of the slider. There is no direct relationship between the specific position of the moving platform, and the moving platform has a good ability to realize the posture.

Third, the structure is driven by internal and external pairs, and the two fixed-length drive rods are driven by external pairs, which can be easily calibrated for thermal effects on their lengths. The controllable telescopic axis that controls the attitude change of the moving platform is driven by the inner pair, which makes it easier to control the attitude of the moving platform. The use of a plane frame instead of a single support rod (fixed-length drive rod) can greatly improve the rigidity of the structure.

Fourth, the connection mode of the parallel closed-chain structure is single-hinge connection. Because the single hinge is easy to manufacture, the processing precision is very high, thereby ensuring the hinge precision of the mechanism.

Fifth, the structure is a simple planar structure with low manufacturing cost and convenient assembly and disassembly. Part of the drive adopts external auxiliary drive, which is easy to produce with standard parts. By adding movement and rotation of the table, it can be turned into a four or five degrees of freedom machine tool. In addition, a rotation function can be added to the side where the motor is installed on the moving platform to become a six-degree-of-freedom machine tool, which is suitable for the processing requirements of most complex workpieces

Sixth, the structure is simple, and it is easy to conduct in-depth theoretical analysis and obtain optimal design parameters. It is also easy to control it in real time.

Seventh, the structure of the controllable telescopic shaft with independent functions, the linear guide rod adopts a hollow structure, which is convenient for the ball screw to enter, not only the structure is simple, but also the center is symmetrical, which reduces various errors generated during movement, and can greatly improve the performance of the machine tool. Comprehensive accuracy.

Claims (8)

1, the inside and outside secondary combination drive virtual-shaft machine tool structure of a kind of gantry slide block type, comprise 2 vertically arranged guide rails, 2 controlled slide blocks that are installed in the guide rail, drive 2 linear drives unit that slide block moves in guide rail, 2 fixed length drive bars, the moving platform of 1 installation cutting tool, 1 workbench that workpiece is installed, it is characterized in that said 2 fixed length drive bar one ends are linked together by hinge, the other end is connected with a said slide block respectively; Also comprise 1 driven sliding block that also is installed in the said wherein guide rail, 1 controlled telescopic shaft, said driven sliding block and said one controlled slide block are fixed together by setpoint distance, one end of this driven sliding block and said controlled telescopic shaft is fixed, the other end of controlled telescopic shaft is connected with said moving platform one end, the other end of this moving platform links to each other with the plane connecting frame hinge point of two regular lengths, form closed linkage in parallel, said workbench closed linkage in parallel with this on driving is independent mutually.

2, machine tool structure as claimed in claim 1 is characterized in that, the driving of lathe is inside and outside secondary combination drive, and wherein the driving of 2 fixed length drive bars is outer secondary the driving, and the driving of controlled telescopic shaft is interior secondary the driving.

3, machine tool structure as claimed in claim 1 is characterized in that, the driven sliding block installation site of the controlled telescopic shaft of said connection is positioned at above the controlled slide block of same guide rail, following or same position.

4, machine tool structure as claimed in claim 1 is characterized in that, the link position and the guide rail of said controlled telescopic shaft and driven sliding block depart from certain distance.

5, machine tool structure as claimed in claim 1 is characterized in that, said moving platform is the moving platform with a rotating function.

6, machine tool structure as claimed in claim 1, the width extending of 2 fixed length drive bars becomes plane framework or surface plate.

7, machine tool structure as claimed in claim 1 is characterized in that, said workbench is by slide unit, the workbench of the rotatable and translation that motor, guide rail, turntable are formed.

8, machine tool structure as claimed in claim 1, it is characterized in that, said controlled telescopic shaft is by the cylinder blanket of an end opening, servomotor in the enclosure is installed successively, the linear guide of hollow inserts and to be subjected to motor-driven ball-screw and ball nut in the guide rod and the coupling that linear guide and ball nut are fixed together is formed.

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