Mounting structure for components with different coefficients of thermal expansion

Abstract

This invention provides a mounting structure for components with different coefficients of thermal expansion that can suppress loosening of screws and other fasteners due to the concentration of tensile and compressive stresses caused by thermal expansion, as well as plastic deformation of components. [Solution] The mounting structure of the present invention is a structure for attaching a second member 20 having different coefficients of thermal expansion to a first member 10, and comprises a ball spline shaft 50a fixed to the first member through a through hole formed in the approximate center of the second member, and a ball spline nut 50b attached to the ball spline shaft and fixed to the second member, and low friction support members 60 are provided between the first member and the second member, located in a radial direction toward the end of the second member with the approximate center as the center point, and on the same circumference with the center point as the center point, and outside the range of gravity movement of the device placed on the second member, at least three locations.

Description

Technical Field

[0001] The present invention relates to an attachment structure for members having different coefficients of thermal expansion, for example, an attachment structure for members having different coefficients of thermal expansion, such as fixing an XY stage device made of an iron-based material to a pedestal made of an aluminum alloy.

Background Art

[0002] An XY stage device (actuator) installed in a processing chamber of an aluminum alloy, such as a vacuum spraying device, is mainly composed of stainless steel or steel from the viewpoint of strength. When spraying treatment is performed in a vacuum spraying container, due to the difference in the coefficients of thermal expansion between the bottom plate of the vacuum spraying container that fixes the XY stage device made of an aluminum alloy and the attachment member that attaches the XY stage device to the bottom plate, a load is generated on bolts or the like that fix the two. If such a difference in the coefficient of thermal expansion becomes large, there is a risk of problems such as damage to the fixing member and deformation of the fixing member of the XY stage device.

[0003] The following Patent Document 1 relates to a coupling structure for two members having different coefficients of thermal expansion. The first member is attached to the second member having a different coefficient of thermal expansion at a plurality of attachment locations to couple the two members. In the coupling structure for two members having different coefficients of thermal expansion, the first member is rigidly coupled to the second member at one attachment location, and is loosely fitted at other attachment locations so as to be movable in the vertical and horizontal directions and unable to escape. A coupling structure for two members having different coefficients of thermal expansion is disclosed.

[0004] The technique described in the following Patent Document 1 allows horizontal movement (play) by engaging the end of the L-shaped metal fitting constituting the second member with a notch provided in the first member for a horizontal change (change in dimensions due to temperature change) due to the difference in the coefficient of thermal expansion. Therefore, the technique described in the following Patent Document 1 has a problem that a notch must be provided in the first member and the end of a part of the member constituting the second member must be processed into an L-shape.

[0005] Furthermore, the first and second members are rigidly connected at one point by screw fastening. As a result, tensile and compressive stresses are concentrated at the screw fastening point, leading to problems such as screw loosening, plastic deformation of the seating surface, and fatigue failure of the screw member. Repeated minute displacements due to expansion differences can cause minute slippage (fretting) at the contact surface, resulting in the generation of oxidation and wear particles. Moreover, because the rigid connection point restrains the expansion difference, warping occurs throughout the entire member, which can cause a deterioration in accuracy in XY stage devices and other applications where flatness is required. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Published Utility Model Gazette H2-102553 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] Therefore, in view of the above, the object of the present invention is to provide a mounting structure for members with different coefficients of thermal expansion in which loosening of screws, etc., due to the concentration of tensile and compressive stress does not occur, the members do not undergo plastic deformation, and the generation of wear particles due to minute sliding at the contact surfaces between the members is also suppressed. [Means for solving the problem]

[0008] To solve the above problems, the present invention provides a mounting structure for members with different coefficients of thermal expansion, wherein a second member is attached to a first member having a different coefficient of thermal expansion at multiple mounting locations, A ball spline shaft fixed to the first member through a through hole formed in the approximate center of the second member, and a ball spline nut attached to the ball spline shaft and fixed to the second member, The low-friction support members are provided between the first member and the second member, positioned radially toward the end of the second member with the approximate central portion as the center point, and located at least three locations on the same circumference centered on the center point, outside the range of gravity movement of the device placed on the second member. [Effects of the Invention]

[0009] As described above, the present invention provides a mounting structure for members with different thermal expansion coefficients that prevents loosening of screws and the like due to the concentration of tensile and compressive stresses, prevents plastic deformation of the members, and suppresses the generation of wear particles due to minute sliding at the contact surfaces between the members. [Brief explanation of the drawing]

[0010] [Figure 1(a)] This is a plan view of two parts with different coefficients of thermal expansion fixed together with bolts. [Figure 1(b)] This is a cross-sectional view AA shown in Figure 1(a). [Figure 2(a)] This is a plan view of a mounting structure for two parts with different coefficients of thermal expansion, which is an embodiment of the present invention. [Figure 2(b)] This is a view from arrow BB of a mounting structure for two parts with different coefficients of thermal expansion, which is an embodiment of the present invention. [Figure 2(c)] Figure 2(b) shows an example of point contact support in detail of section C. [Figure 2(d)] Figure 2(b) shows an example of the ball roller support in detail of section C. [Figure 2(e)] Figure 2(b) shows an example of the slide plate (sliding bearing) support in detail of section C. [Figure 2(f)] Figure 2(b) shows an example of air support in detail for section C. [Figure 3(a)] This is a plan view of a mounting structure in which a stainless steel XY stage device is fixed to the bottom plate of an aluminum alloy processing chamber, which is an embodiment of the present invention. [Figure 3(b)] This is a front view of the mounting structure shown in Figure 3(a). [Figure 3(c)] It is a D-D arrow view shown in FIG. 3(a).

Embodiments for Carrying Out the Invention

[0011] Hereinafter, embodiments of the mounting structure of members having different coefficients of thermal expansion according to the present invention will be described based on the drawings. The drawings schematically show the mounting structure of members having different coefficients of thermal expansion, and the dimensions and dimensional ratios on the drawings do not necessarily match the actual dimensions and dimensional ratios. Also, unless otherwise specified, duplicate explanations will be omitted as appropriate, and the same members may be given the same reference numerals.

[0012] FIG. 1 is a plan view of a conventional mounting structure in which two parts having different coefficients of thermal expansion are fixed by bolts. Member A10 is, for example, the bottom plate of a vacuum spraying container, and member B20 is a fixing member for a device fixed on member A10, for example, a linear actuator. The center (center of gravity) and the four corners of member B20 are fixed to member A10 by bolts 30.

[0013] FIG. 1(b) is a cross-sectional view taken along the line A-A shown in FIG. 1(a). As shown in FIG. 1(b), the bolt 30 is inserted through a through-hole formed in member B20 and screwed into a threaded hole formed in member A10, whereby member 20 is fastened and fixed (rigidly connected) to member 10.

[0014] In such a conventional mounting structure, when members A10 and B20 thermally expand as described above, tensile and compressive stresses concentrate on the screw tightening part due to the difference in their coefficients of thermal expansion, resulting in problems such as loosening of the screws, plastic deformation of the seating surface, and fatigue failure of the screw members. Also, when minute displacements due to the expansion difference are repeated, minute slip (fretting) occurs on the contact surface, resulting in problems such as generation of oxidized powder and wear powder. Furthermore, since the rigid connection part restrains the expansion difference, warping occurs in the entire member, which causes deterioration of accuracy in an XY stage device etc. where flatness is required.

[0015] FIG. 2(a) is a plan view of an attachment structure of two components having different coefficients of thermal expansion according to an embodiment of the present invention. FIG. 2(b) is a cross-sectional view taken along line B-B of the attachment structure of two components having different coefficients of thermal expansion according to an embodiment of the present invention. As shown in FIGS. 2(a) and 2(b), a ball spline shaft 50a is provided at the center of a member B20. The ball spline shaft 50a is inserted through a through hole formed in the member B20 and press-fitted or bolted to a member A10. A ball spline nut 50b is mounted on the upper side of the ball spline shaft 50 (inside the member b20), and the ball spline nut 50b is fixed to the member 20b. By connecting the member A10 and the member B20 with a ball spline shaft and a ball spline nut, it is not a fixed connection like screwing, so axial sliding is allowed and minute positional deviations can be absorbed. Further, it is possible to reduce stress concentration on the joint due to the difference in the coefficient of thermal expansion during heating, and to prevent relative rotation of the members due to fluctuations in the center of gravity position accompanying the operation of the XY stage device.

[0016] As shown in FIG. 2(a), between the member A10 and the member B20, low friction support members 60 are disposed at each end on three extension lines radially arranged at intervals of 120° around the ball spline shaft 50a as a center point. With such low friction support members 60 as contact points, it is a structure that supports the contact portions of the member A10 and the member B20 that relatively move due to the difference in the coefficient of thermal expansion with low friction.

[0017] In the present embodiment, the low friction support members 60 are provided at three locations. However, it is preferable that the number of support points for the relatively moving members be three or more so that the center of gravity balance is uniform, and the number of support points is determined according to the load. Further, when the center of gravity position fluctuates due to its operation, such as in an XYZ stage device, it is important to provide support points outside the center of gravity movement range.

[0018] Figures 2(c) to 2(f) show examples of the low-friction support member 60 of section C shown in Figure 2(b). Figure 2(c) shows low-friction support using metal balls 61 such as steel, and Figure 2(d) shows an example of low-friction support using a ball roller 62. The ball roller has a structure in which steel balls are interposed between an outer cylinder and an inner ring, and the load is supported by the rolling of these balls.

[0019] Figure 2(e) shows an example of low-friction support using a slide plate (sliding bearing), and Figure 2(f) shows an example of low-friction support using air. The slide plate (sliding bearing) 63 is a structure that is interposed between relative moving members and supports the load while reducing friction at the sliding surface. A lubricating film or self-lubricating material is used on the contact surface. Low-friction support using air (air support structure) is a structure that supplies compressed air to the air bearing 64 through a compressed air passage 65 and supports with no contact or extremely low friction.

[0020] Figure 3(a) is a plan view of a mounting structure in which a stainless steel XY stage device is fixed to the bottom plate of an aluminum alloy processing chamber, which is an embodiment of the present invention. Figure 3(b) is a front view of the mounting structure shown in Figure 3(a). Figure 3(c) is a cross-sectional view of the CC shown in Figure 3(a).

[0021] At the center of the XY stage base plate 25 of the XY stage device, a ball spline shaft 50a is press-fitted into the bottom surface 15 of the processing chamber through a through hole formed in the XY stage base plate 25. Four low-friction support members 60 are provided outside the center of gravity movement range 100 of the XY stage device, as shown in Figures 3(b) and 3(c).

[0022] The X-axis actuator 70 is guided by the X-axis support guide rail 75a and moves in the X-axis direction. The Y-axis actuator 80 is positioned and fixed on the X-axis support guide slider 75b in a direction perpendicular to the driving direction of the actuator 70. The sample stage 90, which is placed on the Y-axis actuator 70, moves in the X-axis and Y-axis directions due to the movement of the X-axis actuator 70 and the Y-axis actuator 80. Although the center of gravity of the XY stage base plate 25 changes due to such movement, the mounting structure of members with different coefficients of thermal expansion in this embodiment suppresses relative rotation of the XY stage base plate 25 with respect to the processing chamber bottom member 15, stress concentration on the ball spline shaft 50a, and warping of the XY stage base plate 25 due to such changes in the center of gravity.

[0023] [Explanation of Symbols]

[0024] 10 Component A 15 Processing chamber bottom member 20 Component B 25 XY Stage Base Plate 30 volts 50a Ball spline shaft 50b Ball Spline Nut 60 Low-friction support member 61 metal ball 62 Ball Roller 63 Plain bearings 64 Air bearings 65 Compressed air flow path 70 X-axis actuator 75a X-axis support guide rail 75b X-axis support guide slider 80 Y-axis actuator 90 Sample stage 100 Center of gravity movement range 100X Center of gravity movement range in the X direction 100Y Y-direction center of gravity movement range

Claims

[Claim 1] A mounting structure for members with different coefficients of thermal expansion, wherein a second member with a different coefficient of thermal expansion is attached to a first member at multiple mounting locations, The second member comprises a ball spline shaft fixed to the first member through a through hole formed in the approximate center of the second member, and a ball spline nut attached to the ball spline shaft and fixed to the second member. A mounting structure for members with different coefficients of thermal expansion, characterized in that low-friction support members are provided between the first member and the second member, positioned radially toward the end of the second member with the approximate central portion as the center point, and located at least three locations on the same circumference centered on the center point, outside the range of gravity movement of the device placed on the second member.

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