Linear motor double-drive high-precision machine tool

Abstract

The invention relates to the field of machine tool mechanical equipment, and discloses a linear motor double-drive high-precision machine tool which comprises a machine tool body, a stand column, a carriage, a spindle box, an electric spindle, a workbench and a driving device. The machine tool body and the stand column are formed by casting mineral materials and form a machine tool fixing base, the planker moves on the stand column in the X-axis direction through a driving device, the workbench moves on the machine tool body in the Y-axis direction through the driving device, the spindle box moves on the planker in the Z-axis direction through the driving device, and the spindle box is arranged on the planker. An electric spindle is installed in the spindle box, and the driving devices are two sets of linear motor modules which are symmetrically installed. The influence of heat source temperature rise on the machine tool precision is reduced, the influence of driving reverse clearance on the machine tool precision is reduced, the influence of linear motor stator and rotor magnetic attraction on the machine tool precision is reduced, and therefore the geometric precision, the positioning precision, the repeated positioning precision and the minimum feeding amount of the machine tool are improved.

Description

Technical Field

[0001] The present invention relates to the field of machine tool mechanical equipment, and in particular to a linear motor dual-drive high-precision machine tool. Background Art

[0002] Optical lens molds, optical imaging molds, automobile lamp molds, precision medical equipment molds and infrared laser parts mirror super-precision. Most of the above parts are curved surface processing with high surface finish, which requires the machine tool to have high-speed dynamic response, high acceleration, high stability, micro-feed and super-precision processing capabilities.

[0003] The bed, column, carriage, spindle box and worktable of traditional machine tools are all cast in gray cast iron. At room temperature, the thermal expansion coefficient of HT300 gray cast iron is about 9.6×10 -6 / K, the thermal conductivity is about 47.5W / m / K. When the temperature of the machine tool rises, the parts cast in gray cast iron on the machine tool will undergo significant thermal deformation, thus affecting the accuracy of the machine tool.

[0004] The transmission devices of traditional machine tools mostly use ball screws or gear racks. The above two types of transmission methods have the following two main disadvantages. On the one hand, when the temperature of the machine tool rises, it will cause the transmission chain to heat up. On the other hand, long-term use will cause mechanical wear of the transmission chain and increase the reverse clearance, thereby causing reduced machine tool accuracy and instability.

[0005] The application of mineral castings and linear motors can effectively solve the above-mentioned problems of traditional machine tools. Machine tools driven by linear motors have become the mainstream products of high-speed and high-precision machine tools. At present, most machine tools using linear motors adopt single-drive. Since there is a magnetic attraction between the stator and the mover of the linear motor, the magnetic attraction of the linear motor is about 3 times its driving force. The magnetic attraction of the linear motor will cause the connected machine tool parts to deform, thereby affecting the accuracy of the machine tool. In order to obtain high precision and high stability of the machine tool, it is necessary to strengthen the rigidity of the machine tool parts connected to the linear motor to resist the influence of the magnetic attraction of the linear motor on the accuracy of the machine tool. Strengthening the rigidity of the machine tool parts will increase the cross-section, mass and cost of the machine tool, and at the same time reduce the high-speed dynamic performance of the machine tool. Summary of the invention

[0006] In view of the deficiencies in the prior art, the present invention provides a linear motor dual-drive high-precision machine tool, which solves the problem in the prior art that the temperature rise of the heat source and the magnetic attraction of the linear motor cause deformation of machine tool parts and components, making it difficult to obtain a high-precision machine tool.

[0007] To achieve the above-mentioned purpose, the present invention provides the following technical solution: a linear motor dual-drive high-precision machine tool, comprising a bed, a column, a carriage, a spindle box, a worktable, an electric spindle and a drive device, the bed and the column are both cold-casted by mineral materials, and the carriage, the spindle box and the worktable are all made of ductile iron parts.

[0008] Furthermore, precision cooling pipelines are pre-buried inside the bed and the columns.

[0009] Furthermore, the carriage, spindle box and worktable castings are subjected to multiple tempering and vibration aging treatments to reduce the residual internal stress of the castings to less than 20 MPa.

[0010] Furthermore, the carriage is driven by the X-axis driving device to perform X-axis motion on the column along the X-axis guide rail.

[0011] Furthermore, the workbench is driven by the Y-axis driving device to perform Y-axis motion on the bed along the Y-axis guide rail.

[0012] Furthermore, the spindle box is driven by the Z-axis driving device to perform Z-axis motion on the carriage along the Z-axis guide rail, and two sets of nitrogen balancing cylinders are arranged on the spindle box to balance the weight of the counterweight Z-axis moving parts.

[0013] Furthermore, an electric spindle is arranged inside the spindle box, the electric spindle adopts an air static pressure bearing, and the spindle box is provided with a precision cooling pipeline for cooling the electric spindle.

[0014] Furthermore, the X-axis, Y-axis, and Z-axis driving devices are two sets of symmetrically installed linear motor modules.

[0015] Furthermore, the stators and movers of the linear motors of the X-, Y-, and Z-axis drive devices are all equipped with precision coolers.

[0016] Compared with the prior art, the present invention provides a linear motor dual-drive high-precision machine tool, which has the following beneficial effects.

[0017] The bed and columns of the present invention are formed by cold casting of mineral materials, and no internal stress is released after cold casting; for bed and columns with the same cross-section, the bed and columns cast by mineral castings (solid casting) are 50% heavier than the bed and columns cast by gray cast iron (cavity casting), so that the natural frequency and damping property of the fixed base of the machine tool composed of the bed and columns are significantly improved.

[0018] The X-axis, Y-axis and Z-axis driving devices of the present invention all adopt two sets of symmetrically installed linear motor modules, which reduces the influence of the magnetic attraction force of the stator and mover of the linear motor on the accuracy of the machine tool.

[0019] The heat sources of the machine tool of the present invention are all provided with precision cooling pipelines, and each heat source is individually controlled by a water cooler to control the temperature difference of various parts of the machine tool; the thermal conductivity of the mineral casting is about 3W / m / K, which is only 6% of that of gray cast iron, reducing the thermal deformation of the machine tool caused by the temperature rise of the heat source and improving the accuracy and stability of the machine tool. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a structural schematic diagram of a linear motor dual-drive high-precision machine tool disclosed in the present invention;

[0021] Figure 2 It is a schematic diagram of the structure of the X-axis driving device disclosed in the present invention;

[0022] Figure 3 It is a schematic diagram of the structure of the Y-axis driving device disclosed in the present invention;

[0023] Figure 4 It is a schematic diagram of the structure of the Z-axis driving device disclosed in the present invention;

[0024] Figure 5 It is a schematic diagram of the structure of a single-drive drive device of a linear motor machine tool in the prior art;

[0025] Figure 6 It is a schematic diagram of the magnetic attraction force application of the dual-drive linear motor disclosed in the present invention;

[0026] Figure 7 It is a schematic diagram of the magnetic attraction force application of a single-drive linear motor of a linear motor machine tool in the prior art.

[0027] In the figure: 1. bed; 11. Y-axis guide rail; 12. Y-axis stator base; 121. Y-axis stator precision cooler; 122. Y-axis linear motor stator; 13. precision cooling pipeline; 2. column; 21. X-axis guide rail; 22. X-axis stator base; 221. X-axis stator precision cooler; 222. X-axis linear motor stator; 23. precision cooling pipeline; 3. carriage; 31. Z-axis guide rail; 32. Z-axis stator base; 321. Z-axis stator precision cooler; 322, Z-axis linear motor stator; 33, X-axis mover base; 331, X-axis mover precision cooler; 332, X-axis linear motor mover; 4, spindle box; 41, precision cooling pipeline; 42, Z-axis mover base; 421, Z-axis mover precision cooler; 422, Z-axis linear motor mover; 43, nitrogen balance cylinder; 5, workbench; 51, Y-axis mover base; 511, Y-axis mover precision cooler; 512, Y-axis linear motor mover; 6, electric spindle. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] See also Figure 1 A linear motor dual-drive high-precision machine tool comprises a bed 1, a column 2, a carriage 3, a spindle box 4, a workbench 5, an electric spindle 6 and X-, Y- and Z-axis driving devices. The bed 1 and the column 2 are made of mineral materials by cold casting. There is no subsequent internal stress release of the cold-cast mineral castings. The thermal expansion coefficients of mineral castings and cast iron parts are similar, but the thermal conductivity is only 6% of that of cast iron parts, which reduces the temperature rise and thermal deformation of the machine tool affected by the heat source. The bed 1 and the column 2 are solid mineral castings, which are 50% heavier than cavity cast iron parts. The bed 1 and the column 2 form a fixed base of the gantry structure, which improves the natural frequency and vibration resistance of the machine tool. The slide 3, the spindle box 4 and the worktable 5 are all made of ductile iron parts. After multiple tempering and vibration aging treatments, the residual internal stress of the castings is reduced to less than 20MPa. The tensile strength of ductile iron is 40% higher than that of gray cast iron, which improves the main machine rigidity and stability of the machine tool and ensures the accuracy of the machine tool.

[0030] See also Figure 1-4 A precision cooling pipeline 13 is pre-buried inside the bed 1, a precision cooling pipeline 23 is pre-buried inside the column 2, a precision cooling pipeline 41 is arranged inside the spindle box 4, the X-axis drive device is equipped with an X-axis stator precision cooler 221 and an X-axis mover precision cooler 331, the Y-axis drive device is equipped with a Y-axis stator precision cooler 121 and a Y-axis mover precision cooler 511, and the Z-axis drive device is equipped with a Z-axis stator precision cooler 321 and a Z-axis mover precision cooler 421. The above 6 cooling pipelines are equipped with 6 water coolers to precisely control the cooling capacity according to the temperature rise of each heat source, so as to ensure that the overall temperature difference of the machine tool is controlled within ±2°C during the operation of the machine tool, thereby reducing the influence of the temperature rise and thermal deformation of the heat source on the accuracy of the machine tool.

[0031] See also Figure 2 The X-axis driving device adopts two sets of symmetrically installed linear motor dual drives. The column 2 is provided with an X-axis guide rail 21 and two sets of oppositely installed X-axis stator bases 22. The X-axis stator base 22 is provided with a precision cooler 221 and an X-axis linear motor stator 222 in sequence; the carriage 3 is provided with an X-axis mover base 33, and both sides of the X-axis mover base 33 are provided with a precision cooling cooler 331 and an X-axis linear motor mover 332 in sequence.

[0032] Among them, the linear motor stator and mover generate equal and opposite magnetic attraction forces.AX1 and F AX2 Acting on both sides of the X-axis mover base 33, F AX1 and F AX2 The two values ​​are equal and opposite in direction, and they cancel each other out, thus reducing the deformation of the carriage 3 caused by the magnetic attraction of the linear motor; F AX1 ' and F AX2 ' Acting on two groups of X-axis stator bases 22 respectively, the force causes the X-axis stator base 22 to bend and deform, reducing the deformation of the X-axis guide rail 21 caused by the magnetic attraction force of the linear motor.

[0033] See also Figure 3 The Y-axis driving device adopts two sets of symmetrically installed linear motor dual drives. The bed 1 is provided with a Y-axis guide rail 11 and two sets of oppositely installed Y-axis stator bases 12, and the Y-axis stator base 12 is sequentially provided with a precision cooler 121 and a Y-axis linear motor stator 122; the workbench 5 is provided with a Y-axis mover base 51, and both sides of the Y-axis mover base 51 are sequentially provided with a precision cooling cooler 511 and a Y-axis linear motor mover 512.

[0034] Among them, the linear motor stator and mover generate equal and opposite magnetic attraction forces. AY1 and F AY2 Acting on both sides of the Y-axis mover base 51, F AY1 and F AY2 The two values ​​are equal and opposite in direction, and they cancel each other out, thus reducing the deformation of the workbench 5 caused by the magnetic attraction of the linear motor; F AY1 ' and F AY2 ' Acting on two groups of Y-axis stator bases 12 respectively, the force causes the Y-axis stator base 12 to bend and deform, reducing the deformation of the Y-axis guide rail 11 caused by the magnetic attraction force of the linear motor.

[0035] See also Figure 4 The Z-axis driving device adopts two sets of symmetrically installed linear motor dual drives. The carriage 3 is provided with a Z-axis guide rail 31 and two sets of oppositely installed Z-axis stator bases 32. The Z-axis stator base 32 is provided with a precision cooler 321 and a Z-axis linear motor stator 322 in sequence; the spindle box 4 is provided with a Z-axis mover base 42, and both sides of the Z-axis mover base 42 are provided with a precision cooling cooler 421 and a Z-axis linear motor mover 422 in sequence.

[0036] Among them, the linear motor stator and mover generate equal and opposite magnetic attraction forces. AZ1 and F AZ2 Acting on both sides of the Z-axis mover base 42, F AZ1 and F AZ2 The two values ​​are equal and opposite in direction, and they cancel each other out, thus reducing the deformation of the spindle box 4 caused by the magnetic attraction of the linear motor; FAZ1 ' and F AZ2 ' Acting on two groups of Z-axis stator bases 32 respectively, the force causes the Z-axis stator base 32 to bend and deform, reducing the deformation of the Z-axis guide rail 31 caused by the magnetic attraction force of the linear motor.

[0037] See also Figure 5 The prior art linear motor machine tool Z-axis drive device adopts a set of linear motor single drive. The Z-axis linear motor mover 422 and the precision cooler 421 are directly mounted on the spindle box 4, the Z-axis linear motor stator 322 and the precision cooler 321 are directly mounted on the carriage 3, and the linear motor magnetic attraction F AZ and F AZ 'It acts directly on the spindle box 4 and the carriage 3, increasing the deformation of the spindle box 4 and the carriage 3 caused by the magnetic attraction of the linear motor, and reducing the accuracy of the machine tool.

[0038] Performance test: Testing the deformation of a machine tool caused by the magnetic attraction force of the dual-drive linear motor disclosed in the present invention and the single-drive linear motor in the prior art.

[0039] See also Figure 6 The X-axis drive device is two sets of dual-drive linear motors (single linear motor driving force F = 1810N, magnetic attraction force F A =5950N), the Y-axis and Z-axis drive devices are two sets of dual-drive linear motors (a single linear motor driving force F = 905N, magnetic attraction force F A =2980N).

[0040] Test method: Fix the base of the bed 1 and follow the Figure 2-4 The magnetic attraction force is applied at the position and direction of the magnetic attraction force on the X, Y and Z axes as shown in the figure, and the deformation of each point (C1, C2, C3, C4 and C5) of the machine tool is measured. The measurement results are shown in Table 1.

[0041] Table 1. Test data of the deformation of machine tools caused by the magnetic attraction of dual-drive linear motors

[0042] Location Electric spindle Workbench X-axis guide rail Y-axis guide rail Z-axis guide rail Point C1 C2 C3 C4 C5 Deformation (μm) 0.53 0.09 0.59 0.09 0.53

[0043] See also Figure 7 The X-axis drive device is a set of single-drive linear motors (single linear motor driving force F = 3620N, magnetic attraction force F A =12000N), the Y-axis and Z-axis drive devices are both a set of single-drive linear motors (single linear motor driving force F=1810N, magnetic attraction force F A =5950N).

[0044] Test method: Fix the base of the bed 1 and follow the Figure 5The magnetic attraction force of the linear motor is applied at the position and direction shown in the figure, and the deformation of each point (C1, C2, C3, C4, C5) of the machine tool is measured. The measurement results are shown in Table 2.

[0045] Table 2. Test data of the deformation of machine tools caused by magnetic attraction of single-drive linear motor

[0046] Location Electric spindle Workbench X-axis guide rail Y-axis guide rail Z-axis guide rail Point C1’ C2’ C3’ C4’ C5’ Deformation (μm) 3.57 1.31 0.81 0.31 1.67

[0047] From the comparison between Table 1 and Table 2, it can be seen that, with the same machine tool host, the same driving force, and the same test points, the deformation of the machine tool caused by the dual-drive linear motor magnetic attraction structure is smaller than that caused by the single-drive linear motor magnetic attraction structure, thereby ensuring the high precision of the machine tool.

[0048] The installation method, connection method or setting method disclosed in this embodiment are all common mechanical methods, and they can be implemented as long as they can achieve their beneficial effects. In addition, the electrical components appearing in the text are all electrically connected to the main controller and the power supply. The main controller is a conventional known device, and there is an existing disclosed power connection technology. Therefore, the text will not go into too much detail on its specific structural composition and working principle.

[0049] It should be noted that in this article, the orientation or position relationship indicated is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be understood as a limitation on the present application.

[0050] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0051] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A linear motor dual-drive high-precision machine tool, comprising a bed (1), a column (2), a carriage (3), a spindle box (4), a workbench (5), an electric spindle (6) and a drive device; the drive device is two sets of linear motor modules symmetrically installed on the three axes of X, Y and Z.

2. A linear motor dual-drive high-precision machine tool according to claim 1, characterized in that: The bed (1) and the column (2) are both formed by cold casting of mineral materials; a precision cooling pipeline (13) is pre-buried in the bed (1); a precision cooling pipeline (23) is pre-buried in the column (2); the column (2) is fixed to the bed (1); and the two form a fixed base of the machine tool gantry structure.

3. A linear motor dual-drive high-precision machine tool according to claim 1, characterized in that: The carriage (3), the spindle box (4) and the workbench (5) are all cast from ductile iron, and the castings are subjected to multiple tempering and vibration aging treatments to reduce the residual internal stress of the castings to less than 20 MPa.

4. A linear motor dual-drive high-precision machine tool according to claim 1, characterized in that: The bed (1) is provided with a Y-axis guide rail (11) and two sets of Y-axis stator bases (12) installed opposite to each other, and the Y-axis stator base (12) is provided with a Y-axis stator precision cooler (121) and a Y-axis linear motor stator (122) in sequence; the workbench (5) is provided with a Y-axis mover base (51), and the Y-axis mover precision cooler (511) and the Y-axis linear motor mover (512) are symmetrically provided on both sides of the Y-axis mover base (51); the workbench (5) is driven by the linear motor of the Y-axis driving device to perform Y-axis motion on the bed (1) along the Y-axis guide rail (11).

5. The linear motor dual-drive high-precision machine tool according to claim 1, characterized in that: The column (2) is provided with an X-axis guide rail (21) and two sets of X-axis stator bases (22) installed opposite to each other, and the X-axis stator base (22) is provided with an X-axis stator precision cooler (221) and an X-axis linear motor stator (222) in sequence; the carriage (3) is provided with an X-axis mover base (33), and the X-axis mover precision cooler (331) and the X-axis linear motor mover (332) are symmetrically provided on both sides of the X-axis mover base (33); the carriage (3) is driven by the linear motor of the X-axis drive device to perform X-axis motion on the column (2) along the X-axis guide rail (21).

6. A linear motor dual-drive high-precision machine tool according to claim 1, characterized in that: The carriage (3) is provided with a Z-axis guide rail (31) and two groups of Z-axis stator bases (32) installed opposite to each other, and the Z-axis stator base (32) is provided with a Z-axis stator precision cooler (321) and a Z-axis linear motor stator (322) in sequence; the spindle box (4) is provided with a Z-axis mover base (42), and the Z-axis mover precision cooler (421) and the Z-axis linear motor mover (422) are symmetrically provided on both sides of the Z-axis mover base (42); the spindle box (4) is driven by the linear motor of the Z-axis driving device to perform Z-axis motion on the carriage (3) along the Z-axis guide rail (31), and the spindle box (4) is provided with two groups of nitrogen balance cylinders (43), and the nitrogen balance cylinders (43) are used to balance the weight of the counterweight Z-axis moving parts.

7. The linear motor dual-drive high-precision machine tool according to claim 1, characterized in that: An electric spindle (6) is arranged inside the spindle box (4), and a precision cooling pipeline (41) is arranged inside the spindle box (4).

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