JP2006250305A - Linear motion thrust cylindrical roller bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide structure sufficiently suppressing a wear volume between outer circumferential faces of a plurality of cylindrical rollers 1 and a mating face and sufficiently securing rolling fatigue lives of the faces. <P>SOLUTION: A condition of 0.7≤X≤0.95 is satisfied, when an axial dimension of each cylindrical roller 1 is L<SB>t</SB>, an axial length of a cylindrical face part formed to the outer circumferential face of teach cylindrical roller 1 is L<SB>s</SB>, an axial dimension of each of crowning parts 15, 15 is L<SB>c</SB>, and an axial dimension of each of chamfered parts 16, 16 is C, and a parameter X=L<SB>s</SB>/(L<SB>t</SB>-2C) is satisfied. By adopting the structure, the above problem is solved. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The linear motion type thrust cylindrical roller bearing according to the present invention is incorporated between a pair of members constituting various mechanical devices and relatively displaced in a linear direction, and supports a thrust load applied between these two members. However, it is used to make the relative displacement in the linear direction between these two members free.

  As a linear motion type thrust cylindrical roller bearing that can be used in the above-described applications, for example, those shown in FIGS. The direct acting type thrust cylindrical roller bearing shown in FIGS. 1 to 4 includes a plurality of cylindrical rollers 1 and 1 and a cage 2 for holding the cylindrical rollers 1 and 1. Among these, the plurality of cylindrical rollers 1, 1 are parallel to each other in the same virtual plane (a plane parallel to the paper surface of FIG. 1, indicated by a one-dot chain line α in FIGS. They are arranged concentrically. Specifically, as shown in FIG. 1, the cylindrical rollers 1, 1 adjacent to each other in a direction (vertical direction in FIG. 1) orthogonal to the axial direction (left-right direction in FIG. 1) of the cylindrical rollers 1, 1. Thus, the phases in the axial direction are shifted by about a half pitch and arranged in a staggered manner.

  The cage 2 is formed in a square plate shape as a whole, and each of the cage 2 has a plurality of substantially rectangular pockets 3 and 3 that can hold the cylindrical rollers 1 and 1 so as to roll one by one. Prepare. Such a cage 2 is configured by combining a pair of elements 4a and 4b, each of which is formed into a square shape by punching and bending each metal plate. That is, each of the elements 4a and 4b has a pair of square plates 5a and 5b formed by bending the widthwise end edges of each of the plates 5a and 5b at right angles in the same direction. Parts 6a and 6b. Then, as shown in FIG. 3, the flanges 6a and 6b are fitted to each other, and the leading edges (in FIG. 3) of the flanges 6a and 6a constituting the element 4a on one side (upper side in FIG. 3). The two elements 4a and 4b are non-separated from each other by caulking a plurality of positions (lower edge) to the outer peripheral surface of the other element 4b (downward in FIG. 3). In this state, each of the pockets 3 and 3 is configured by aligning a plurality of substantially rectangular through holes 7 and 7 formed on the flat plate portions 5a and 5b constituting the elements 4a and 4b. is doing. That is, each of these pockets 3 and 3 is constituted by a pair of through holes 7 and 7 facing each other.

Moreover, it exists in the width direction (the up-down direction of FIGS. 1-2, the left-right direction of FIG. 4) of each pocket 3, 3 among the inner edges of each through-hole 7, 7 which comprises each said pocket 3, 3. Engaging protrusions 9 and 9 projecting toward the center of each of the through holes 7 and 7 are provided at the intermediate portions in the longitudinal direction of the pair of straight edge portions 8 and 8 parallel to each other. Then, the W _p (width dimension of the opening of the pockets 3, 3) these engaging projections 9,9 interval between, smaller than the diameter D ₁ of the outer peripheral surface of each cylindrical roller 1, 1 (W _p <and D ₁₎ was. By performing such dimensional restrictions, the cylindrical rollers 1 and 1 are prevented from falling off from the inside of the pockets 3 and 3. In the course of manufacturing a linear motion type thrust cylindrical roller bearing as shown in the figure, the cylindrical rollers 1 and 1 are placed in the pockets 3 and 3 while elastically deforming the engaging protrusions 9 and 9, respectively. Or when the pair of elements 4a and 4b constituting the cage 2 are combined with each other, the two elements 4a and 4b are sandwiched between the elements 3a and 4b in the pockets 3 and 3, respectively. Deploy.

  When the direct acting type thrust cylindrical roller bearing configured as described above is used, the cylindrical rollers 1 and 1 are sandwiched between a pair of planes 10 and 11 (shown only in FIG. 4) arranged in parallel to each other. To do. And in this state, while supporting the thrust load applied between a pair of members 12 and 13 (shown only in FIG. 4) provided with these both planes 10 and 11, these both members 12 and 13 It is possible to make relative displacement in directions parallel to the virtual plane α and perpendicular to the axial direction of the cylindrical rollers 1 and 1 (up and down direction in FIG. 1, front and back direction in FIG. 3, and left and right direction in FIG. 4). .

The outer peripheral surfaces of the cylindrical rollers 1 and 1 and the flat surfaces 10 and 11 are in line contact with each other. In order to ensure the rolling fatigue life of these surfaces, the line contact portions between these surfaces are used. It is important that excessive surface pressure based on edge load does not act on both ends of the plate. For this reason, in the case of the structure shown in the figure, the axial direction of the outer peripheral surface of each cylindrical roller 1 is shown in detail in FIG. 5 (the radial dimension is exaggerated as compared with the axial dimension). Crowning is applied to the ends. That is, each of these cylindrical rollers 1 has an axially intermediate portion on the outer peripheral surface as a cylindrical surface portion 14, similarly, portions near both axial ends are crowned portions 15, 15, respectively, and each of these crowning portions 15, 15 and both axial end surfaces. The chamfered portions 16 and 16 are continuous portions. As described above, in the generatrix shape of the outer peripheral surface of each cylindrical roller 1, the portion corresponding to the cylindrical surface portion 14 is a linear portion parallel to the central axis of each cylindrical roller 1. Further, the portions corresponding to the crowning portions 15 and ₁₅ are curved portions having a sufficiently large curvature radius R15 that is inclined in a direction in which the outer diameter becomes smaller toward the both sides in the axial direction. Further, a portion corresponding to each of the chamfered portions 16, 16 is inclined in a direction in which the outer diameter decreases toward the both sides in the axial direction, and a curved portion having a sufficiently small radius of curvature R ₁₆ (R ₁₆ << R ₁₅ ) It has become. Further, the straight line portions and the curved line portions are smoothly continuous with each other. Then, by providing the crowning portions 15, 15 between the cylindrical surface portion 14 and the chamfered portions 16, 16 in this way, line contact between the outer peripheral surface of the cylindrical rollers 1, 1 and the flat surfaces 10, 11 is achieved. An excessive surface pressure based on the edge load is prevented from acting on both ends of the portion.

尚、この（１）式の右辺の各記号の意味は、以下の通りである。
Ｋ：摩耗係数
Ｗ：上記各面同士の接触部に作用している法線方向の荷重（ころ荷重）
Ｌ：滑り距離
Ｈ：摩耗が生じた面の硬さ By the way, when the direct acting type thrust cylindrical roller bearing as described above is used, the outer peripheral surfaces of the cylindrical rollers 1 and 1 are in rolling contact with the flat surfaces 10 and 11, respectively. However, depending on the operating conditions, slippage may occur at the contact portion between these surfaces. In this way, when slippage occurs at the contact portions between the surfaces, the total volume V of the wear powder generated on each surface can be expressed by the following equation (1) (see, for example, Non-Patent Document 1). ).

The meaning of each symbol on the right side of the equation (1) is as follows.
K: Wear coefficient W: Load in the normal direction acting on the contact portion between the above surfaces (roller load)
L: Sliding distance H: Hardness of the surface on which wear has occurred

尚、この（２）式の右辺のＬ_r は、転がり距離である。この（２）式から分かる様に、上記各面の摩耗深さｄは、これら各面同士の線接触部の長さＳ_c に反比例する。従って、これら各面の摩耗は、この線接触部の長さＳ_c を大きくする事により、減少させる事ができる。 Further, as described above, but in line contact with each other and the outer peripheral surface and the respective planes 10, 11 of each cylindrical roller 1,1, when the length of the line contact portion and S _c, equation (1) From the above relationship, the wear depth d of each of the surfaces in contact with each other can be expressed by the following equation (2).

Note that L _{r on} the right side of the equation (2) is a rolling distance. As can be seen from this equation (2), the wear depth d of the respective surfaces is inversely proportional to the length S _c of the contact lines of these surfaces to each other. Therefore, wear of these surfaces is, by increasing the length S _c of the line contact portion, can be reduced.

Accordingly, next, described with regard to whether it increases in the how the length S _c of the line contact portion. Length S _c of the line contact portion is changed by the size of the roller load W. That is, when the roller load W is zero (W = 0), the cylindrical rollers 1 and 1 are not elastically deformed. Only the planes 10 and 11 are in contact with each other. Accordingly, in this case, the length S _c of the line contact portion is the axial dimension L _s of the cylindrical surface portion 14. On the other hand, when the roller load W is not zero (W> 0), the cylindrical rollers 1 and 1 are elastically deformed in the direction in which they are crushed between the planes 10 and 11. The outer peripheral surfaces of the cylindrical rollers 1 and 1 contact not only the cylindrical surface portion 14 but also at least a part of the crowning portions 15 and 15 (portions adjacent to the cylindrical surface portion 14) in contact with the flat surfaces 10 and 11. It becomes like. Therefore, in this case, the length S _c of the line contact portion has an axial dimension L _s of the cylindrical surface portion 14, at least a portion of the axial dimension (of the portion axially of the respective crowning portions 15 The dimension is the sum of the above and the larger the roller load W). Therefore, as can be seen from these relationships, the length S _c of the line contact portion increases the ratio of the axial dimension L _s of the cylindrical surface portion 14 to the axial dimension L _t of the cylindrical rollers 1, 1. You can make it bigger.

However, if the ratio of the axial dimension L _s of the cylindrical surface portion 14 to the axial dimension L _t of the cylindrical rollers 1 and 1 is excessively increased, the ratio of the axial dimension L _c of the crowning portions 15 and 15 is increased. It will not be possible to secure enough. As a result, when the roller load W is increased, the entire crowning portions 15 and 15 are easily brought into contact with the flat surfaces 10 and 11 and are based on edge loads at both ends of the line contact portion. Since excessive surface pressure is likely to act, it is not preferable.

Yamamoto, Kaneda, "Tribology", Science and Engineering, February 25, 2001, 1st edition, 4th edition, p189

  The direct acting type thrust cylindrical roller bearing according to the present invention takes these circumstances into consideration, by restricting the ratio of the axial dimension of the cylindrical surface part (a pair of crowning parts) to the axial dimension of each cylindrical roller The present invention has been invented to realize a structure that can reduce the wear amount between the outer peripheral surface and the mating surface of each cylindrical roller and ensure the rolling fatigue life of each surface at a high level.

The direct acting type thrust cylindrical roller bearing of the present invention has a plurality of cylindrical rollers in which the respective central axes are arranged in parallel or concentrically within the same virtual plane, and each of these cylindrical rollers is held in a freely rolling manner. And a cage having a plurality of rectangular pockets. And each said cylindrical roller makes the axial direction intermediate part of an outer peripheral surface a cylindrical surface part, and also makes a part near an axial direction both ends each crowning part, and each continuous part of each said crowning part and axial direction both end surface makes a chamfering part, respectively. Yes.
In particular, in the case of the direct acting type thrust cylindrical roller bearing of the present invention, the axial dimension of each cylindrical roller is L _t , the axial dimension of the cylindrical surface portion is L _s, and the axial dimension of each chamfered portion. Is C and the parameter X = L _s / (L _t −2C), the condition of 0.7 ≦ X ≦ 0.95 is satisfied.

  In the case of the direct acting type thrust cylindrical roller bearing of the present invention configured as described above, since the parameter X is restricted to an appropriate range (0.7 ≦ X ≦ 0.95), a plurality of cylinders Reduction of the amount of wear between the outer peripheral surface of the roller and the mating surface and securing of the rolling fatigue life of each surface can be achieved at a high level.

An evaluation test performed in the process of completing the present invention will be described. In this example, a direct acting type thrust cylindrical roller bearing having the basic configuration shown in FIGS. 1 to 5 was employed as a sample for performing this evaluation test. In addition, the dimension of each part is as follows.
Width dimension W _h of cage 2: 70 mm
Total number of cylindrical rollers 1: Axial dimension L _t of 25 cylindrical rollers 1: 8 mm
Diameter D _{1 of} cylindrical roller 1 (cylindrical surface portion 14): 5 mm
Axial dimension C of chamfered portion 16: 0.5 mm

  A pair of planes 10 and 11 sandwiching the cylindrical rollers 1 and 1 are parallel to the virtual plane α and perpendicular to the axial direction of the cylindrical rollers 1 and 1 (left and right in FIG. 4). In this case, the strokes s in which the cylindrical rollers 1 and 1 roll / slide back and forth with respect to the planes 10 and 11 are set to 2 mm.

Then, the axial direction when the dimension and the ratio of L _s while varying the outer peripheral surface and the respective plane 10 of the cylindrical rollers 1,1 cylindrical portions 14 relative to the axial dimension L _t of each cylindrical roller 1,1 11 is obtained by the above equation (2), the parameter X {= L _s / (L _t −2C)} and the reduction amount of the bearing width W _b due to wear (FIG. 4) Sought the relationship. FIG. 6 shows the result. In FIG. 6, the amount of decrease in the bearing width W _b is represented by a ratio in which the amount of decrease when the parameter X is 0.43 is “1” (the vertical axis in the figure). In the present embodiment, the outer circumferences of the cylindrical rollers 1 and 1 when the ratio of the axial dimension L _s of the cylindrical surface portion 14 to the axial dimension L _t of the cylindrical rollers 1 and 1 is variously changed. By calculating the rolling fatigue life of the surface and each of the planes 10 and 11 using a conventionally known calculation formula, the parameter X and the rolling fatigue life (when X = 0.4, the rolling fatigue life is obtained. The relationship with the life ratio “1”) was determined. FIG. 7 shows the result. 6 to 7, the radius of curvature R 15 of the pair of crowning portions 15, ₁₅ is the edge load at the contact portion between each of these crowning portions 15, 15 and each of the above planes 10, 11. It was set so that it would be the maximum in the range where no occurrence occurred.

First, as is apparent from the results shown in FIG. 6, the amount of decrease in the bearing width W _b due to wear decreases as the parameter X increases. Therefore, it can be said that it is preferable to increase the parameter X as much as possible in order to suppress the reduction amount of the bearing width W _b due to this wear.

However, as is clear from the results shown in FIG. 7, in the interval until the parameter X reaches a value of less than 0.9, the rolling fatigue life (life ratio) of each surface increases as the parameter X increases. However, in the section where the parameter X exceeds a value of less than 0.9, as the parameter X increases, the rolling fatigue life (life ratio) of each surface decreases rapidly. Show the trend. The reason why such a tendency is exhibited in the section where the parameter X exceeds a value of less than 0.9 is that if the parameter X exceeds a value of less than 0.9, the axis of the pair of crowning portions 15 and 15 The direction dimension _Lc is insufficient, and the edge portions on the opposite sides of each of the crowning portions 15 and 15 have edges at the line contact portions between the outer peripheral surfaces of the cylindrical rollers 1 and 1 and the planes 10 and 11, respectively. This is because an excessive surface pressure based on the load is generated. In particular, at the point where the parameter X = 1 (X becomes maximum), the axial dimension L _c of each of the crowning portions 15, 15 becomes zero (the crowning portion disappears), and the above-described portions are formed at both ends of the cylindrical surface portion 14. Since the chamfered portions 16 and 16 are continuous, the edge load is maximized, and the rolling fatigue life (life ratio) in the section is minimized. Therefore, it is not preferable to make the parameter X too large (too close to 1) from the viewpoint of securing this rolling fatigue life (life ratio).

  Therefore, in the case of the present invention, based on the results shown in FIGS. 6 to 7 described above, the amount of wear between the outer peripheral surfaces of the cylindrical rollers 1 and 1 and the flat surfaces 10 and 11, The parameter X is set to 0.7 ≦ X ≦ 0.95 {preferably 0.775 ≦ X ≦ 0.925 (more preferably) so that the rolling fatigue life of the surface can be ensured at a high level. Is regulated within the range of 0.85 ≦ X ≦ 0.9)}.

  In addition, when implementing the linear motion type thrust cylindrical roller bearing of the present invention, the planar shape of the cage is not limited to a square (see FIG. 1), and various shapes according to the application can be adopted. In addition, regarding the dimensions, various dimensions can be adopted according to the application. Furthermore, in the embodiment described above, the inner surface shape of each pocket formed in the cage is a shape that can prevent the cylindrical roller from falling off from the inside of each pocket. The inner surface shape may be a shape that cannot prevent the cylindrical roller from falling off.

The top view which shows an example of the linear motion type thrust cylindrical roller bearing used as the object of this invention. The A section enlarged view of FIG. BB sectional drawing of FIG. The figure which expands and shows the DD cross section of FIG. The partial side view of a cylindrical roller which exaggerates and shows the dimension of radial direction compared with the dimension of an axial direction. The graph which shows the relationship between the parameter X calculated | required by performing theoretical calculation in the process of completing this invention, and the reduction _| decrease ratio of the bearing width Wb by wear. Similarly, the graph which shows the relationship between the parameter X and the life ratio of each surface.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cylindrical roller 2 Cage 3 Pocket 4a, 4b Element 5a, 5b Flat plate part 6a, 6b Eaves part 7 Through-hole 8 Straight edge 9 Engagement protrusion 10 Plane 11 Plane 12 Member 13 Member 14 Cylindrical part 15 Crowning part 16 Chamfering Part

Claims (1)

A plurality of cylindrical rollers in which the respective central axes are arranged in parallel or concentrically within the same virtual plane, and a cage having a plurality of rectangular pockets for holding the respective cylindrical rollers in a rollable manner. Each cylindrical roller has an axially intermediate portion of the outer peripheral surface as a cylindrical surface portion, and also portions near both axial ends are crowned portions, and continuous portions of these crowning portions and both axial end surfaces are chamfered portions, respectively. A linear thrust cylindrical roller bearing, wherein the axial dimension of each cylindrical roller is L _t , the axial dimension of the cylindrical surface portion is L _s, and the axial dimension of each chamfered portion is C A direct acting type thrust cylindrical roller bearing characterized by satisfying a condition of 0.7 ≦ X ≦ 0.95 when X = L _s / (L _t −2C).

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