CN1182003A - Machine tool structure with dioctahedral frame virtual shaft - Google Patents

Abstract

The invention belongs to the technical field of mechanical manufacturing. The invention includes six controllable telescopic axes, a moving platform equipped with cutting tools, a static workbench and a frame equipped with workpieces, and the frame is a large and small double octahedron structure, wherein the large octahedron includes a top triangular frame, a bottom triangular frame and a frame . The small octahedron includes a small triangular frame supporting the workbench and a frame connecting the small triangular frame with the bottom triangle. The present invention has better rigidity, higher precision and faster feed speed. And improve the flexibility and mobility of the machine tool processing process.

Description

Double Octahedron Frame Type Virtual Axis Machine Tool Structure

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.

In the field of mechanical manufacturing, traditional machine structures, such as cutting machine tools, all 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 tool must have a high-rigidity bulky and heavy bed, columns and other supporting components and a high-precision guide rail system fixed to the supporting components, resulting in heavy weight, high price, and difficulty in handling and 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 structure 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.

At present, the machine tool industry at home and abroad has adopted various corresponding countermeasures in the face of increasingly complex processing shapes and special processing requirements. In order to meet the requirements of modern processing objects, traditional machine tools need to rely on more complex and bulky structures and expensive fixtures to complete the task. As a result, the manufacturing cycle is long, the cost is high and the manufacturing quality is difficult to guarantee. In recent years, a virtual axis machine tool has appeared, which uses 6 telescopic axes that can be controlled in parallel to replace the traditional fixed guide rail system; adopts a frame structure to replace the traditional heavy components such as the bed and columns.

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 aimed at the control of six controllable axes. For a certain space pose requirement of the tool, there are corresponding length values of six telescopic axes corresponding to it. That is to say, the virtual axis machine tool realizes the processing requirements by controlling the actual length of the six controllable axes. The tool pose described by the Cartesian coordinate system becomes a description of the virtual axis system for the machine tool, and the length of the six telescopic axes is its actual control axis, so it is called a virtual axis machine tool. This machine tool provides a brand-new processing equipment, which fundamentally changes the relative motion mode of the tool and the workpiece, increases the flexibility of the tool operation movement, and makes the equipment have greater process flexibility and control maneuverability.

A typical example of foreign existing technology is the six-axis machine tool of the US INGERSOLL company (US patent 5,392,663), which has a separate octahedral frame support structure, and the upper ends of the six controllable telescopic axes are respectively connected to the top nodes of the octahedral frame. The lower end is connected with the moving platform used for the spindle on which the tool is installed.

The telescopic shaft described in this patent has a complex structure, with a spherical hinge at one end and a drive motor at the other end, and a large ball fixed outside the middle of the controllable telescopic shaft that is connected to the top of the frame. The installation and manufacture are difficult and complicated, relatively speaking, the effective length of the controllable telescopic shaft is shortened, and the reachable area of the processing range is limited.

In addition, in this US patent, only a single octahedron frame of the machine tool is proposed, which is used to install the telescopic shaft, the moving platform and the workbench. The workbench is supported by beams with variable cross-sections, but its defect is that the process system cannot be completely composed of two-force rods, which limits the improvement of the rigidity of the machine tool.

Since the processing range of this type of machine tool changes with the vertical direction (positive direction), there is only a maximum processing range at a fixed positive value, and as the positive value increases and decreases, its processing range will vary. will shrink accordingly.

The purpose of the present invention is to overcome the deficiencies of the prior art, and adopt a parallel closed-chain mechanism to design a machine tool structure with multiple functional virtual axes such as cutting, transfer, and assembly, so that it has better rigidity, Greater precision and faster feed rates. And improve the flexibility and mobility of the machine tool process.

A double-octahedron frame-type virtual axis machine tool structure designed by the present invention includes 6 controllable telescopic axes, a dynamic platform equipped with cutting tools and a static workbench equipped with workpieces, supporting and connecting the telescopic axes and the dynamic platform The frame is characterized in that said frame is a large and small double octahedron structure connected to each other by two force rods, wherein the large octahedron includes a top triangular frame composed of 12 rods, which are parallel to the top triangle and have vertex angles misaligned The bottom triangular frame at the 60° angle, and the frame that connects each vertex of one triangle with two adjacent vertices of another triangle; the small octahedron includes a small triangular frame that supports the worktable by 3 rods, and A frame and a bottom triangular frame that connects each vertex of the small triangular frame to two adjacent vertexes of the bottom triangle and the bottom triangle frame formed by 6 rods; The large octahedron frame of the structure is connected, and its telescopic end is connected with the said moving platform;

The small triangular frame in the present invention can be located in the top triangular frame and the bottom triangular frame to form an embedded double octahedron frame structure. Said small triangular frame can also be positioned under the bottom triangular frame to form an external double octahedron frame structure. The controllable telescopic shaft consists 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. A coupler with ball nuts fixed together; one end of the linear guide rod protrudes out of the shell to form a telescopic end, and its end face is a spherical hinge connected with the moving platform. The closed end of the shell is a fixed end, and its end face is fixed with a virtual hinge and Said frames are connected at the top. Said workbench can also include a lifting device associated with it, the lifting device consists of a bracket and a plurality of linear guide bushes installed on the bracket, a plurality of linear guide rails inserted in the guide sleeve and a ball screw and The matching ball nut and the servo motor that drives the ball nut to rotate.

The content of the invention is embodied in three aspects: the structure of the controllable telescopic shaft, the frame of the double octahedron machine tool and the lifting system of the additional workbench.

Below in conjunction with accompanying drawing, introduce the content of the present invention in detail.

Fig. 1 is a schematic diagram of the structure of the telescopic shaft of the present invention. In the figure, 28 is a servo motor, which can drive the ball screw 16 installed on the bearing 26 to rotate according to the requirements. Both the bearing 26 and the servo motor 28 are installed in the casing 24 . The linear guide bush 14 is fixed on the outer wall 22 , and the outer wall 22 is fixed on the box body 24 , so there is no relative movement between the linear guide bush 14 and the outer wall 22 of the box body 24 . Under the constraints of the linear guide sleeve 14, the linear guide rod 12 can only move linearly in the axial direction and cannot rotate around the axis. The coupling 18 fixes the linear guide 12 and the ball nut 20 together, so the ball nut 20 cannot rotate around the axis. When the ball screw 16 rotates, the linear guide rod 12 is driven by the ball nut 20 to extend or shorten in the axial direction.

The controllable telescopic axis system shown in Fig. 1 is connected to the moving platform and the top of the frame of the machine tool respectively by means of a ball joint 10 at the telescopic end and a Hooke hinge 30 at the fixed end. The hollow structure adopted by the linear guide rod 12 enables the ball screw 16 to enter conveniently, which greatly simplifies the mechanical structure. The possibility of motion errors is reduced.

Fig. 2 is a top view of the frame of the machine tool of the present invention, the top triangle is composed of three rods 32; the bottom triangle is composed of three rods 34. The angle between the top triangle 32 and the bottom triangle 34 is staggered by 60°, and the nodes of the two triangles are connected by six rods 36 to form a large regular octahedron. When a force is applied on any node, each rod of the octahedral frame is only subjected to tension and compression, not to bending moment, so it has high rigidity.

Fig. 3 is a schematic side view of the frame of the machine tool of the present invention, showing the structure of the embedded double octahedron frame. The triangle 40 consists of three screw rods 40 . The angle between this triangle 40 and the bottom triangle 34 is staggered by 60°, and the two triangle nodes are connected by six rods 38 to form an octahedron with a small top and a big bottom. The static table 42 is supported by three supports 44 located at three nodes of the triangle 40 . When the static table 42 is subjected to external forces such as cutting forces, the three nodes of the triangle 40 are stressed and transmitted to the frame, and each rod of the octahedral frame is only subjected to tension and compression, not to bending moments, so it has Very high rigidity.

In Fig. 3, one end of the six controllable telescopic shafts 43 is connected to each node of the triangle 32 on the octahedron frame, and the other end is connected to the moving platform 45, so that a combination of lengths corresponding to the six controllable telescopic shafts 43, There is a specific pose of the moving platform 45, and the lengths of the six controllable telescopic axes 43 are constantly changing, which will bring about the movement and rotation of the moving platform 45. The cutting tool 47 installed on the moving platform 45 can process workpieces on the static working platform 42 flexibly.

Fig. 4 is a schematic side view of another form of machine tool frame of the present invention, showing the structure of an external double octahedron frame. The triangle 46 is composed of three rods 46, the angle between this triangle 46 and the large triangle 34 is staggered by 60°, and the nodes of the two triangles are connected by six rods 50 to form an octahedron with a large upper part and a smaller lower part. The static table 42 is supported by three supports 48 positioned at three nodes of the triangle 46 . When the static table 42 is subjected to external forces such as cutting force, the three nodes of the triangle 46 are stressed and transmitted to the frame, and each rod of the octahedral frame is only subjected to tension and compression, and is not subject to bending moment, so it has Very high rigidity.

Fig. 5 is a structural schematic diagram of the workbench lifting device. Two or three linear guide rails 60 are fixed below the workbench 42 , and the linear guide sleeve 62 is connected with a support 64 . In order to maintain accurate translation along the Z direction when the workbench 42 moves up and down, a lead screw 52 is also fixed below the workbench 42, and the nut 54 is connected with the bracket 64. When the servo motor 58 drives the nut 54 through the gear pair 56, the work Platform 42 just moves in translation up and down. Since the movement range of the moving platform driven by the six controllable telescopic axes can be simplified as a sphere, when the lifting device is added, the movement range of the moving platform is expanded to a cylinder with the same diameter as the sphere, which significantly improves the performance of the machine tool.

The present invention has the following effects:

First, 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. Comprehensive accuracy.

Second, the double octahedral frame structure, so that the four major components of the process system: various forces between machine tools, tools, workpieces, and fixtures are transmitted to each rod of the octahedral frame through the nodes of the frame, so the entire frame It only bears tension or pressure, without torque, which reduces the machining error caused by the force deformation of the machine tool. Can greatly improve the rigidity of the machine tool.

Third, the large octahedron frame is connected to the ends of the six controllable telescopic axes; the front ends of the six controllable telescopic axes are connected to the moving platform equipped with cutters. The two ends adopt the joint connection method, which is convenient for disassembly and assembly, and is conducive to maintenance.

Fourth, the workbench is fixed on the top surface of the built-in or external octahedral frame, so that the external comprehensive force on the workbench acts on each node on the top surface of the frame, so as to avoid the bending moment of the frame, which is different from the existing ones. Compared with the parallel mechanism machine tool, the rigidity of the machine tool is improved.

Fifth, a lifting device that can move up and down is attached to the bottom of the workbench, so that the maximum cross-section of the movement space of this type of machine tool can be fully utilized, and the actual processing range of the machine tool is expanded.

Description of drawings:

Fig. 1 is a structural schematic diagram of a controllable telescopic shaft.

Fig. 2 is a schematic top view of the frame structure of the double octahedron machine tool, and the operation part of the machine tool is omitted in the figure.

Fig. 3 is a schematic side view of a double-octahedron machine tool frame structure (embedded double-octahedron structure), in which the lifting system of the workbench is omitted.

Fig. 4 is a schematic side view of the frame structure of the double octahedron machine tool (external double octahedron structure), in which the lifting part of the workbench and the operating part of the machine tool are omitted.

Fig. 5 is a structural schematic diagram of the workbench lifting system.

Fig. 6 is a schematic diagram of an embodiment of a controllable telescopic shaft.

Fig. 7 is a schematic diagram of an embodiment of a double octahedron frame, in which the lifting part of the workbench is omitted.

Fig. 8 is a schematic diagram of an embodiment of the workbench lifting system.

A structural embodiment of a double-octahedron frame type virtual axis machine tool designed by the present invention, as shown in Figure 6, is described as follows in conjunction with each figure:

Fig. 6 is a schematic structural diagram of a controllable telescopic shaft according to an embodiment of the present invention. The ball hinge 10 is eliminated by the adjustable ball hinge seat 8, and the linear guide bush 12 is restricted by the sliding bush 14 and cannot rotate but can only move axially. The servo motor 28 drives the lead screw 16 so that the nut 20 drives the linear guide sleeve 12 to extend or shorten in the axial direction. One end of the controllable telescopic shaft utilizes the stop surface of the ball hinge seat 8 to be connected with the moving platform 45, and the other end utilizes the stop surface of the Hooke hinge holder 31 to connect with the octahedron frame top. It is simple to manufacture and convenient to install. The effective length of the controllable telescopic shaft is fully utilized, and the processing range of the machine tool is expanded.

Fig. 7 is a schematic diagram of the overall structure of the embodiment of the present invention. The box body 66 is a hinge connection part at the top of the octahedron frame structure. The triangular faces on the top surface of the octahedron and the triangular faces on the sides are formed by it, and the controllable telescopic shaft is also installed on the box body 66 . The base 68 is a hinge connection part at the bottom of the octahedron frame structure, and each base 68 is connected with 6 two-force rods, through which the triangular faces of the octahedron bottom and the triangular faces of the sides are formed, and the built-in octahedron is also formed. Triangular faces on the sides.

When the tool 47 on the moving platform cuts the workpiece on the workbench 42, the cutting force is transmitted to each two-force rod through each node of the two octahedron frames, so that the rods of the machine tool frame only bear tension or pressure. In the whole closed process system, it has excellent rigidity.

The controllable telescopic shaft 43 is installed between the box body 66 and the moving platform 45 . Different length changes of the controllable telescopic shaft 43 can change the position and posture of the tool 47 on the movable platform 45 to realize cutting motion. The controllable telescopic shaft 43 is easy to install, and the effective length of the controllable telescopic shaft 43 is fully utilized to obtain a larger working space range.

Fig. 8 is a schematic structural diagram of the workbench lifting device according to the embodiment of the present invention. Three linear guide rails 60 are fixed on the lower part of the workbench 42 . Three guide sleeves 62 are connected with support 64, and support 64 is fixed on three nodes of the small triangular plane of built-in or external hanging octahedron. Servomotor 58 drives workbench 42 to move up and down by gear pair 56, makes workbench always be positioned at the maximum diameter cross-section of the spheroid of inner edge of processing reachable space. Expand the processing range from a sphere to a cylinder with the same diameter as the sphere.

Claims (5)

1. A double-octahedron frame-type virtual axis machine tool structure, including 6 controllable telescopic axes, a dynamic platform equipped with cutting tools and a static workbench equipped with workpieces, a frame that supports and connects the telescopic axes and the dynamic platform , it is characterized in that said frame is a large and small double octahedron structure connected to each other by two force rods, wherein the large octahedron includes a top triangular frame composed of 12 rods, which is parallel to the top triangle and has a vertex angle misalignment of 60° The bottom triangular frame of the corner, and the frame that connects each vertex of one triangle with the two adjacent vertices of another triangle; the small octahedron includes a small triangular frame that supports the workbench composed of 3 rods, and consists of 6 Each vertex of the small triangular frame is formed by root rods and the frame and the bottom triangular frame that connect each vertex of the small triangular frame to the adjacent two vertexes of the bottom triangle; The octahedral frame is connected, and its telescopic end is connected with the said moving platform; 2. The machine tool structure according to claim 1, wherein said small triangular frame is located in said top triangular frame and bottom triangular frame, forming an embedded double octahedron frame structure. 3. The machine tool structure according to claim 1, characterized in that an external double octahedral frame structure is formed under the triangular frame at the bottom. 4. The machine tool structure as claimed in claim 1, characterized in that said controllable telescopic shaft consists of a cylindrical shell with one end open, a servo motor installed in the shell in turn, a hollow linear guide rod, inserted into the guide rod to receive The ball screw and ball nut driven by the motor and the coupling that fix the linear guide rod and the ball nut together; one end of the linear guide rod protrudes out of the shell to form a telescopic end, and its end face is a ball joint connected with the moving platform, the shell The closed end is a fixed end, and its end face is fixed with a virtual support hinge to be connected with the said frame top. 5. The machine tool structure according to claim 1, characterized in that said workbench also includes a lifting device associated with it, the lifting device consists of a bracket and a plurality of linear guide sleeves installed on the bracket, inserted into the guide A plurality of linear guide rails in the sleeve, a ball screw, a matching ball nut, and a servo motor that drives the ball nut to rotate.

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