JPH0526337Y2 - - Google Patents

Description

[Detailed explanation of the idea]

- Industrial application field This invention is a rolling bearing that allows two members to move linearly relative to each other under preload by rolling a small diameter ball inserted between the raceway grooves of the two members in the direction of linear movement. There is something about it. - Conventional technology This type of rolling bearing for linear motion ranges from those used in machine tools, which have high rigidity and high running accuracy, to those used in cabinet drawers, which are inexpensive and have relatively high accuracy and rigidity. Various types and uses are known, including those that are not necessary. In the former type of bearing, both the table and the bed are made of thick-walled steel and finished with high-precision machining, resulting in a high-rigidity and high-precision bearing, but it was expensive. On the other hand, the latter type of bearing was inexpensive because the table and bed could be formed from thin steel plates by plastic working, but it lacked rigidity and high accuracy could not be expected. In addition, to compensate for the latter drawback, it is possible to increase the thickness of the raceway member, but how thick should it be to obtain a bearing with high rigidity and precision, assuming plastic working? was unknown. - Purpose of the invention The purpose of the invention is to solve the drawbacks of conventional bearings and provide a lightweight, inexpensive, highly rigid, and highly accurate linear motion rolling bearing. - Means for solving the problem In order to fully meet this requirement, the present invention has the following configuration. (1) A bed in which a raceway groove is formed in the longitudinal direction of at least a part of the outer wall surface of a solid, elongated, thick-walled member, and a raceway groove formed in the inner wall surface that spans the bed and corresponds to the raceway groove. It consists of a thin table with a U-shaped cross section, and a large number of balls with a diameter of 3.175 mm or less inserted between the raceway grooves of these two members. A rolling bearing for linear motion with preload, characterized in that the preload is in the range of 20% to 50%, and the minimum plate thickness directly under the raceway groove is 1/3 or more of the diameter of the rolling element.・Example The drawings in FIGS. 1 to 4 show an example of the invention of the present invention. FIG. 1 is a projection view showing an example of the invention of the present invention, FIG. 2 is a front view of FIG. The figure is a side view of FIG. 2, and FIG. 4 is an enlarged half-sectional view of FIG. 2. As shown in Fig. 1, there is a bed 1 in which raceway grooves 1a are formed on a part of both outer wall surfaces in the longitudinal direction of a solid, elongated thick-walled member, and on both inner wall surfaces corresponding to the raceway grooves 1a. It consists of at least a thin table 2 with a U-shaped cross section in which a raceway groove 2a is formed in a part, and a ball 3 with a diameter of 3.175 mm or less inserted between the raceway grooves of these two members. In addition, the balls 3 are arranged at equal intervals in the raceway groove,
A holder 4 for holding is also incorporated. FIG. 2 is a front sectional view of FIG. 1. Since the present invention uses a thick metal material (for example, alloy steel) for the bed 1, it has much higher rigidity than the thin-walled table 2, and the raceway groove and reference surface can be processed by grinding. , the dimensional accuracy can also be more accurately finished. Moreover, since the table 2 is installed with a preload (with a negative internal clearance), even if there is some accuracy defect in the raceway groove 2a of the thin table 2, the raceway groove of the highly accurate bed 1 will be replaced. 1a, the running displacement and sliding resistance of the bearing can be kept small. FIG. 3 is a side view of FIG. 2. The retainer 4 is set at the center of the raceway groove in the direction of movement, so that the table 2 can stroke the same distance on both sides. Although not shown, stopper devices are generally attached to both ends of the bed 1 to prevent the retainer 4 from moving beyond the bed 1. FIG. 4 is an enlarged view of FIG. 2 with the retainer omitted and is a diagram showing the conditions for plate thickness and shape required to ensure sufficient rigidity of the table 2 as a bearing. The depth of the raceway groove 2a formed on the inner side wall surface of the table 2 is t1, the minimum plate thickness of the table 2 at the bottom of the raceway groove 2a is t2, the plate thickness of the table 2 is t,
Assuming that the diameter of the ball used is Da, various experiments have confirmed that the following specifications should be used to ensure the rigidity of the table. t1=(0.2~0.5)×t t2=>Da/3 Here, _{t1 and t2} are the contact points between the balls and the raceway grooves, and due to the usage of this type of bearing, the contact ellipse at the contact points is thin. Considering the case where the table moves due to deformation, the difference in the amount of deformation with respect to the load is not large between when receiving a downward load and when receiving an upward load, and furthermore, the thin table should be slightly deformed. Consideration has been given to providing an appropriate preload. As a result of conducting an experiment on a test bearing having the specifications shown in Table 1, FIG. 5, and FIG. 6, the results shown in FIG. 7 were obtained. The conditions for t ₁ and t ₂ above were derived from the results of this experiment.

[Table] Figure 5 shows a cross section of the test bearing. Figure 6 shows
It is an enlarged view of a table and a ball part. Figure 7 shows
The measured value of displacement when the table and bed are each mounted on a jig and a downward or upward load is applied to the table. Note that the calculated value is a value calculated by assuming that the table and bed are rigid bodies, and assuming that the elastic deformation of the contact portion between the ball and the raceway is the vertical displacement of the bearing. t ₁ =0.4mm corresponds to 0.36t. t ₂ = 0.7 mm (Da/3 = 0.666), and the plate thickness at the bottom of the raceway groove is thin. As shown in FIG. 7, for a given load, the measured value is larger than the calculated value. Further, the displacement is larger when the load is applied in an upward direction than when the load is applied in a downward direction. The main factor is the deformation of the table sleeve. In order to reduce the inertial force during reciprocating linear motion, we want to reduce the weight of the table as much as possible. Therefore, if the thickness of the table is made thinner, the weight can be reduced, but the displacement becomes larger. Because this type of bearing is used for applications that require light loads and high precision (precision measurement equipment, magnetic head guides for computer external storage devices, semiconductor manufacturing and inspection equipment, etc.), the load for this type of bearing is 2 kgf or less. Yes, the difference in displacement with respect to that load is 1 μm when receiving a downward load and when receiving an upward load.
It is as follows. If a bearing that satisfies the conditions in Table 2 is manufactured, it is possible to provide a bearing that, together with the high rigidity of the bed 1, has little deformation under bearing load and small running displacement. Furthermore, since the thin table 2 can be easily formed from a thin plate by plastic working, it is inexpensive. The implementation of the present invention is not limited to a rolling bearing for finite linear motion as shown in the figure, but an infinite straight line in which an infinite circulation path for balls is formed in the bed and the balls circulate infinitely. It is also possible to use ball bearings for motion. - Effects The present invention has the following effects. By combining a table that can be mass-produced with a bed that is highly rigid, a bearing with high running accuracy can be provided at a low cost. Since the table can be formed by plastic working, it can be manufactured at low cost. Since the table is mounted with a preload (with a negative internal clearance), the accuracy of the bearing is more influenced by the thick and highly accurate bed, resulting in a highly accurate bearing. Since the ball has a small diameter of less than 3.175 mm, it has high accuracy and is lightweight, making it suitable for use conditions that dislike inertia.

[Brief explanation of the drawing]

The drawings in FIGS. 1 to 4 show an embodiment of the present invention. FIG. 1 is a projection view showing an embodiment of the present invention, FIG. 2 is a front sectional view of FIG. 1, and FIG. 3 is a front sectional view of FIG. Second
The side view of the figure, and FIG. 4 is a half sectional view that is an enlarged view of FIG. 2. 5 and 6 are schematic diagrams of the experimental apparatus, and FIG. 7 is a diagram of the experimental results. 1...Bed, 2...Table, 1a, 2a...
...Race groove, 1b, 2b...Mounting hole, 3...Ball, 4...Cage, t...Table thickness, t1
... Depth of the table raceway groove, t2 ... Minimum plate thickness of the table raceway groove portion, Da ... Diameter of the ball.

Claims (1)

[Claims for Utility Model Registration] At least a bed in which a raceway groove is formed in the longitudinal direction on a part of the outer wall surface of a solid, elongated, thick-walled member, and an inner wall surface that spans the bed and corresponds to the raceway groove. It consists of a thin table with a V-shaped cross section and a raceway groove formed on the top, and a large number of balls with a diameter of 3.175 mm or less inserted between the raceway grooves of these two members, and the thin table has a plate thickness of t. , the depth of the raceway groove is t ₁ , t-t ₁ = t ₂ , the diameter of the ball is Da
A rolling bearing for linear motion with preload, characterized in that t ₁ =(0.2 to 0.5)×t t ₂ =>Da/3.