JPH08303459A - Guide rail of linear guide device - Google Patents

Abstract

PURPOSE: To provide a guide rail of a linear guide device which can reduce to the utmost deformation of a load ball rolling groove due to fastening of a fitting bolt of a guide rail, so as to extremely highten the motion accuracy of a slider. CONSTITUTION: Where the height of a guide rail is (a), the depth of the counterbore part 7 of a bolt hole is (b), and the dimension from the center line position of a load ball rolling groove 3 positioned most nearby the bottom face 1c of the rail to the bottom face of the rail is (c), the depth of the counterbore part 7 of the bolt hole is set so as to satisfy the following relation: 0.2<=(a-b)/c<=0.5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a guide rail of a linear guide device, and more particularly to a linear guide suitable for a field requiring high precision such as semiconductor industry and machine tool industry by improving the guide rail fixing structure. Regarding the guide rail of the device.

[0002]

2. Description of the Related Art In the conventional linear guide device, the counterbore depth of the bolt for inserting the mounting bolt of the guide rail is generally made as shallow as possible with respect to the rail height in order to keep the rigidity of the guide rail as high as possible. Is. Actually, the spot facing depth is 40 to 50% of the rail height.
If the bolts are tightened when the guide rail is attached to the machine base, the axial force of the bolt compresses the space between the seat surface of the bolt and the bottom surface of the rail, causing elastic deformation. Then, along with this, the load ball rolling groove located on the side surface of the rail (or the load ball rolling groove located on the upper surface of the rail, to be precise, the case where it is formed on the ridge portion where the rail side surface and the rail upper surface intersect) However, in the present specification, it is assumed to be included in the loaded ball rolling groove located on the side surface of the rail.)
Or, the phenomenon that the transfer surface of the groove is vertically deformed at the same period as the mounting bolt interval and wavy appears. When the slider travels on such a guide rail, it affects the motion accuracy of the table.

In particular, when used in fields requiring high precision such as the semiconductor industry and machine tool industry, in order to prevent the corrugation phenomenon of the guide rail, when the loaded ball rolling groove of the guide rail is machined, The guide rail is attached to the processing table under the same conditions as the user's usage conditions to perform groove processing. On the other hand, Japanese Utility Model Laid-Open No. 5-86201 discloses a guide rail of a linear guide device which is capable of obtaining high operation accuracy without being affected by the manner of mounting the guide rail and suppressing an increase in sliding resistance. Mounting structures have been proposed. This one, as shown in Figure 8,
A raceway surface (roller rolling raceway surface) 10b having a substantially V-shaped cross section on the side surface
With respect to the guide rail 10 having the above, the bottom surface 13a of the counterbore portion 13 of the insertion hole 12 of the mounting bolt 11 has the receiving surface 10 located on the bolt tightening direction side of the raceway surface 10b.
It is formed so as to be located on the virtual extension surface 10h of c or on the bolt tightening direction side with respect to the virtual extension surface 10h,
It prevents the opening angle of the raceway surface from being narrowed due to bolt tightening.

[0004]

However, as described above, even if an attempt is made to prevent the corrugation phenomenon of the guide rail by fixing the guide rail and processing the load ball rolling groove under the same conditions as the use conditions of the rail, as described above. , Variations when tightening bolts (even if tightened with a constant torque, the axial force is not always the same depending on the condition of the bolt seat surface)
And the influence of the thickness of the mounting base and the difference in the material, the wavy phenomenon of the loaded ball rolling groove was solved (0.1 μm
There is a problem that you cannot do the following).

Further, as disclosed in Japanese Utility Model Laid-Open No. 5-86201, the bottom surface 13a of the counterbore portion of the bolt insertion hole 12 is shown.
Is located on the virtual extension surface 10h of the V-shaped raceway surface located on the bolt tightening direction side or the virtual extension surface 10
If it is formed so as to be located on the tightening direction side with respect to h, it is not possible to know how deep the position of the counterbore bottom surface 13a may be (extremely, it may be just the bottom surface of the guide rail. However, there is a problem in the strength of the guide rail 10.

As described above, the recent linear guide device is
It tends to be widely used even in fields requiring extremely high movement accuracy on the order of microns, and the straightness of the loaded ball rolling groove of the fixed guide rail, which is directly related to the movement accuracy of the slider, becomes particularly important. Is coming. Therefore, the present invention has been made by paying attention to the above-mentioned conventional problems, and it is possible to minimize the deformation of the load ball rolling groove due to the tightening of the mounting bolts of the guide rail, and it is possible to make the movement accuracy of the slider extremely high, and It is an object of the present invention to provide a guide rail for a linear guide device that ensures the strength of the guide rail.

[0007]

A guide rail of a linear guide device of the present invention which achieves the above object has a spot facing portion and is fixed by inserting a bolt into a bolt hole penetrating from the top surface to the bottom surface of the rail. A guide rail of a linear guide device for supporting a slider fitted so as to be movable in the axial direction through rolling of a large number of balls in an axially loaded ball rolling groove formed on a side surface of the rail, When the height of the guide rail is a, the depth of the counterbore of the bolt hole is b, and the dimension from the groove center line position of the load ball rolling groove located closest to the rail bottom surface to the rail bottom surface is c, The depth of the counterbore of the bolt hole satisfies the relation of 0.2 ≦ (ab) /c≦0.5.

[0008]

According to the present invention, the spot facing depth becomes deeper than in the conventional case. In other words, the depth of the spot facing is increased to make the distance from the bottom surface of the guide rail to the seat surface of the bolt smaller than a certain amount to reduce the elastic deformation amount of this portion, and the absolute deformation of the load ball rolling groove is reduced. Decrease the value. As a result, the corrugation phenomenon of the loaded ball rolling groove can be effectively suppressed, and the movement accuracy of the slider is improved.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a perspective view of a linear guide device equipped with a guide rail 1 of the present invention, FIG. 2 is a sectional view of the guide rail in the axial direction, FIG. 3 is a sectional view of the guide rail in the direction perpendicular to the axis, and FIGS. Is a diagram showing an analysis result by FEM (finite element method), FIG. 6 is an FEM model diagram, and FIG. 7 is a diagram showing an influence of shear stress of the guide rail of the present invention.

As shown in FIG. 1, the linear guide apparatus of this embodiment comprises a guide rail 1 extending in the axial direction and a slider 2 movably supported on the guide rail 1. On both side surfaces 1b of the guide rail 1, load ball rolling grooves 3 are axially formed in two rows, one on each side. Specifically, in the case of this embodiment, the upper load ball rolling groove 3a is the rail upper surface 1a.
Is formed as a 1/4 arc-shaped Gothic arc groove on the ridge line where the side surface 1b intersects, and the lower load ball rolling groove 3b is formed as a 1/2 arc-shaped Gothic arc groove on the rail side surface 1b.

The slider 2 is composed of a slider body 2A and end caps 2B attached to both ends of the slider body 2A. The slider body 2A is shown on the inner surface of both sleeves 4 so as to face the rolling element rolling groove 3 of the guide rail 1. It has a rolling element rolling groove which is not formed, and a rolling element return path which axially penetrates the thick portion of the sleeve portion. On the other hand, the end cap 2B is
The rolling element rolling groove of the slider main body 2A and a rolling element return path parallel to the rolling element rolling path have not-shown curved paths, and these rolling element rolling grooves, rolling element returning paths, and curved paths at both ends are provided. A rolling circuit of rolling elements is formed by. A large number of rolling elements made of, for example, steel balls are loaded in the circulation circuit of the rolling elements, and the slider 2 moves in the axial direction on the guide rail 1 through the rolling of the balls. .
A side seal 5 is provided on the end cap 2B of the slider to prevent foreign matter from entering the inside, and a grease nipple 6 is attached to supply lubricating grease to the balls.

The guide rail 1 has a body portion that penetrates from the upper surface 1a to the bottom surface 1c and has a spot facing portion 7 on the upper portion.
A plurality of bolt holes 8 are provided at predetermined intervals in the lengthwise direction, and the mounting bolts inserted in these bolt holes 8 are tightened so that the bottom surface 7a of the counterbore 7 is attached to the head of the bolt. By pressing strongly on the lower surface, the guide rail 1
Is fixed to a base or the like. Now, as shown in FIG. 3, the height of the guide rail 1 is a, the depth of the counterbore 7 of the bolt hole 8 (the distance from the rail upper surface 1a to the counterbore bottom 7a) is b, and From the groove center line position of the lower loaded ball rolling groove 3b located near the rail bottom surface 1c to the rail bottom surface 1c
Up to c, the counterbore 7 of the bolt hole 8 is
The depth of the bottom surface 7a is 0.2 ≦ (ab) /c≦0.5.
Are formed so as to satisfy the relationship.

The reason why it is necessary to satisfy the above relationship will be described below. The processing of the loaded ball rolling groove 3 of the guide rail 1 is performed by fixing the guide rail 1 to the working table by tightening the bolt inserted into the bolt hole 8 with a prescribed bolt tightening torque as described above. . However, in that case, even if tightened with a constant torque, the bolt axial force will not be constant and will vary depending on the condition of the bolt seat surface.
In addition, the thickness and material of the machine base to which the guide rail 1 is attached are also affected, and the actual situation is not always the same.

Incidentally, as an example, the results obtained by the present inventor experimentally ascertaining how much variation occurs in the deformation amount of the guide rail when the tightening torque variation of a general torque wrench is ± 10%, is shown in FIG. It becomes like 4. In the figure, the abscissa represents the dimensionless quantity expressed by (ab) / c, and F
The vertical axis represents the variation of the deformation amount of the loaded ball rolling groove 3 with respect to the rail bottom surface 1c obtained by EM.

From the results of FIG. 4, the variation of the deformation amount is set to 0.1 μm or less in order to minimize the influence of the variation of the axial force at the time of fastening the bolt and the difference in the thickness and the material of the machine mounting the guide rail 1. It is understood that the depth of the spot facing portion 7 of the bolt hole 8 may be determined so that the value of the dimensionless amount (ab) / c is 0.5 or less. For example,
If the value of the dimensionless amount (ab) / c is set to 0.33, the variation of the deformation amount of the loaded ball rolling groove 3 is 0.75 in the current dimensionless amount (ab) / c. Can be reduced to 1/3.

FIG. 5 shows the deformation amount of the loaded ball rolling groove 3 obtained by FEM, which corresponds to the case where the loaded ball rolling groove 3 is processed without bolting the guide rail 1 to the working table. It is shown for reference. The load applied to the guide rail 1 is a distributed load at the center of the bolt position set to 100% of the static rated load obtained by the linear guide device having a rail width of 23 mm.

FIG. 7 shows the relationship between the dimensionless quantity (ab) / c and the shear stress. Generally, allowable stress is 2 of proof stress σ _B
/ 3 or 1/3 of the tensile strength σ _E , whichever is smaller,
It is of SCM material. From Fig. 7, dimensionless quantity (ab)
When compared with the average value of the shear stress obtained from the value of / c, the range satisfying the allowable stress is 0.2 ≦ (ab) /c≦0.5.

By determining the depth of the counterbore portion of the mounting bolt hole of the guide rail of the linear guide device so as to satisfy the above conditions, there is no problem with the influence on the strength of the rail mounting bolt hole, and the loaded ball rolling groove. The wavy phenomenon of can be solved. In the above embodiment, the guide rail having the ball-loaded rolling groove 3 on each side is described as two guide rails. However, the present invention is not limited to this, and the ball-loaded rolling groove 3 may have one rail on each side or two or more rails on each side. The present invention can also be applied to. Further, in the case of one side each, the ball-loaded rolling groove 3 can also be applied to a groove having a 1/4 circular arc cross section provided on the ridge line portion where the rail upper surface 1a and the side surface 1b intersect. Is in an imaginary groove having a 1/2 arc shape in cross section.

[0019]

As described above, according to the present invention, the dimension from the bottom face of the counterbore of the bolt hole for mounting the guide rail of the linear guide device to the bottom face of the guide rail is a, the height of the guide rail is a, Let b be the depth of the spot facing portion of the bolt hole, and c be the dimension from the groove center line position of the load ball rolling groove located closest to the rail bottom face to the rail bottom face. Is 0.2 ≦ (ab)
Since the setting is made to satisfy the relationship of /c≦0.5, when the bottom of the guide rail is applied to the machine base surface and the bolt is tightened, it is generated by the axial force of the bolt applied to the bottom surface of the counterbore of the bolt hole. Deformation of the guide rail has almost no effect on the groove surface of any loaded ball rolling groove, the deformation of the ball rolling groove is suppressed as much as possible, and the movement accuracy of the slider is improved, and the strength of the guide rail is improved. The effect is also secured.

[Brief description of drawings]

FIG. 1 is a perspective view of an embodiment of a linear guide device including a guide rail of the present invention.

2 is an axial cross-sectional view of the guide rail of FIG.

3 is a cross-sectional view of the guide rail of FIG. 1 in a direction perpendicular to the axis.

FIG. 4 is a diagram showing an analysis result by FEM.

FIG. 5 is a diagram showing an analysis result by FEM.

FIG. 6 (a) is a diagram showing FEM analysis points, and FIG. 6 (b) is F.
It is an EM model figure.

FIG. 7 is a diagram showing the effect of the guide rail of the present invention on shear stress.

FIG. 8 is a cross-sectional view illustrating a guide rail mounting mode of a conventional linear guide device.

[Explanation of symbols]

 1 Guide rail 1a Top surface (of guide rail) 1c Bottom surface (of guide rail) 2 Slider 3 Load ball rolling groove 7 Counterbore part 7a Bottom face of counterbore part

Claims (1)

[Claims] 1. A large number of balls in an axial load ball rolling groove formed on a side surface of a rail, which is fixed by inserting a bolt into a bolt hole having a counterbore portion and penetrating from a rail upper surface to a bottom surface. In a guide rail of a linear guide device that supports a slider fitted so as to be movable in the axial direction via rolling, a height of the guide rail is a, a depth of a counterbore part of the bolt hole is b, and When the dimension from the groove center line position of the loaded ball rolling groove located near the rail bottom surface to the rail bottom surface is c, the depth of the counterbore of the bolt hole is 0.2 ≦.
A guide rail for a linear guide device, which satisfies the relationship of (ab) /c≤0.5.