JP2018091354A - Free ball bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce frictional resistance with respect to rotations of a sphere as further as possible as a free ball bearing to be used for supporting a mobile that moves in one direction.SOLUTION: A free ball bearing 56 comprises: one big sphere 55; a sphere holder 54 which accommodates the sphere 55 in a ball accommodation part 54a having a concave spherical surface; and a number of small balls 80 which are disposed on the concave spherical surface of the ball accommodation part 54a and on which the sphere 55 is mounted. In the ball accommodation part 54a of a holder body 54b, even lines of track grooves forming a movement direction of a mobile are formed in a central part region in a Y direction orthogonal with the movement direction of the mobile (an arrow X direction in Fig 2) on the concave spherical surface. The even lines of track grooves consist of multiple pairs of shallow grooves 81a and deep grooves 81b, each pair including a shallow groove and a deep groove. The shallow groove 81a and the deep groove 81b in each pair are communicated in a communication passage 81c that is an inclined surface of their end portions, such that the small balls 80 can be circulated between the shallow groove 81a and the deep groove 81b.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a free ball bearing having a structure in which one large sphere is placed on many small spheres arranged on a concave spherical surface of a ball housing portion of a sphere holder.

This type of conventional free ball bearing has a structure in which a large number of small spheres receiving large spheres are arranged in such a manner that they are freely laid on a simple concave spherical surface of a spherical holder to cover the concave spherical surface (Patent Document 1, Patent Document 2). ).
This free ball bearing is generally not used when a workpiece moves in one direction because one large sphere supported by a large number of small spheres can rotate in any direction. It is mainly used for a transport table or the like that can transport in any direction in the horizontal direction. In the case of a transfer table, a large number of free ball bearings are distributed on the upper surface of the table.

JP 2003-184871 A JP 07-164078 A

  This type of free ball bearing is different from the structure in which a spherical body that receives a load is directly received by a concave spherical surface, and the spherical body is supported by a large number of small spheres. As described above, the bearing is sometimes used in a transfer table or the like, and is not generally intended to rotate the sphere at a remarkably high speed. Further, since a large number of free ball bearings are arranged in the case of the transfer table, it is generally not assumed that a significantly large load is applied to one free ball bearing.

However, this type of free ball bearing is used for applications that require the sphere to rotate at a significantly high speed, or for applications that require a significant load to be applied, and for a remarkably high speed to rotate and a significantly large load. When used in applications that require a burden, the frictional resistance increases, and there may be cases where a larger power than expected is required as the power to drive the moving body, and there is a possibility that seizure may occur in the free ball bearing. .
This type of free ball bearing, which is generally used when moving in any direction, is used to support a moving body that moves in one direction. Furthermore, it may be necessary to rotate at a significantly high speed and to bear a significantly large load.

  The present invention has been made based on the above background, and as a free ball bearing for use in supporting a moving body moving in one direction, the frictional resistance against rotation of the sphere is small, and the sphere is rotated or remarkably rotated at a high speed. It is an object of the present invention to provide a free ball bearing that can be used for applications that require a large load to be applied, and that it is necessary to rotate a remarkably high speed and to apply a remarkably large load.

In the invention according to claim 1 for solving the above-mentioned problem, a large number of small spheres are arranged on the concave spherical surface of a spherical holder having a ball receiving portion forming a concave spherical surface, and are supported by the multiple small spheres so as to be rotatable. A free ball bearing having a large sphere, and movably supporting a moving body that moves in one direction in contact with the sphere,
The even-numbered track grooves forming the moving body moving direction are formed in at least the central region in the left-right direction orthogonal to the moving body moving direction of the concave spherical surface of the ball housing portion, and the even-numbered track grooves are shallow grooves and deep grooves. And the shallow groove and the deep groove in each pair communicate with each other through a communication passage connecting both ends, and the small sphere in the central region is a shallow groove. It is characterized by being able to circulate between the deep grooves.
In the present invention, the moving body that moves in one direction is not limited to a moving body that moves in the center of gravity. For example, a moving body that rotates without moving the center of gravity, such as a rotating shaft. Including. The moving body moving direction in this case refers to the moving direction of each point on the outer peripheral surface of the rotating body.

  According to a second aspect of the present invention, in the free ball bearing according to the first aspect, the sphere holder is attached to an upper surface of the holder body, the holder body having the ball housing portion and housing the multiple small spheres and one sphere. And a lid for holding the sphere so that a part of the sphere is exposed.

  According to a third aspect of the present invention, in the free ball bearing according to the second aspect, the even-numbered track grooves of the concave spherical surface of the holder main body are only in the central region in the left-right direction orthogonal to the moving body moving direction, Is a concave spherical surface directly along the surface of the sphere.

In the free ball bearing of the present invention, when the moving body moves on the sphere of the free ball bearing, the sphere rotates in the same direction as the moving direction of the moving body on the contact surface with the moving body.
With respect to this sphere, the small sphere in the shallow groove of the pair of track grooves of the shallow groove and the deep groove in the central region contacts the sphere and receives a load, and the sphere rotates on the contact surface with the sphere. It rotates in the direction opposite to the direction (the direction opposite to the moving direction of the moving body). On the other hand, the small sphere in the deep groove is not in a load state because it does not contact the sphere.
Since the track groove forms the moving body moving direction, the small sphere in the shallow groove moves in the direction opposite to the moving body moving direction in the shallow groove while rotating in the direction opposite to the moving body moving direction. Enter the next deep groove through the connecting passage. The small ball that entered the deep groove pushes the small ball in the deep groove, the small ball in the pressed deep groove moves in the deep groove in the moving body moving direction (forward direction), and goes into the shallow groove through the connecting passage on the opposite side enter. As described above, the small sphere that entered the shallow groove from the deep groove rotates in the direction opposite to the rotation direction of the sphere (the direction opposite to the moving direction of the moving object) on the contact surface with the sphere while receiving a load. To do.
Thus, the small sphere circulating between the shallow groove and the deep groove supports the rotation of the sphere while rotating in the reverse direction (the direction opposite to the moving body moving direction) when in the shallow groove.
Since the groove direction of the track groove coincides with the moving body moving direction, the small sphere in the shallow groove that supports the sphere rotating in the moving body moving direction has a rotation axis substantially parallel to the rotating axis of the rotating sphere. Rotate in a manner (reverse direction but rotate in roughly the same direction). Therefore, there is little unnecessary slip between the sphere and the small sphere, and the frictional resistance between the sphere and the small sphere is remarkably small.
In a structure in which a large number of small spheres are arranged on a simple concave spherical surface, the positions of the small spheres are irregular and the rotation direction is irregular, and the frictional resistance against the supporting sphere is also large. According to the free ball bearing, as described above, the small ball rotates in the opposite direction to the rotation direction of the sphere (moving direction of the moving body) (in the opposite direction in a mode having a rotation axis substantially parallel to the rotation axis of the rotating sphere). ), The slip generated between the sphere and the small sphere is small and the frictional resistance is small.

In a structure in which small spheres that rotatably support a sphere are freely laid on the concave spherical surface of the sphere holder like a conventional free ball bearing, the position of each small sphere in the concave spherical surface is not constant. This structure is effective in the case of a transfer table that supports the moving body so as to be movable in an arbitrary direction, but is not efficient when the moving direction of the moving body is one direction.
That is, in the structure where the position of each small sphere supporting the sphere in the concave spherical surface is not constant, the rotation direction of the sphere rotating in the same direction as the moving direction of the moving body does not rotate in the direction opposite to the rotation direction of the sphere. Naturally, small balls are also generated. Such a small sphere slips with respect to the rotation of the sphere and becomes a frictional resistance.
Such frictional resistance can be used for applications that require the sphere to rotate significantly at a high speed, or applications that require a significant load to be loaded, and that it must rotate significantly at a high speed and bear a significant load. When used in certain applications, the frictional resistance increases, and a large amount of power may be required as power for driving the moving body, and there is a possibility that seizure may occur in the free ball bearing.
However, as in the present invention, a plurality of pairs of track grooves each including a pair of a deep groove and a shallow groove forming the moving body moving direction are provided in at least a central region in the left-right direction orthogonal to the moving body moving direction of the concave spherical surface. According to this structure, since the small sphere in the shallow groove in the central region does not move unnecessarily, the rotation in the reverse direction always follows the rotation direction of the sphere correctly (the rotation in the reverse direction on the contact surface). ), And extremely little frictional resistance against the rotation of the sphere.
Therefore, it is used for applications that require the sphere to rotate significantly at high speeds, applications that require a significant load, and applications that require significant rotation and a significant load. Even in this case, large power is not required as power for driving the moving body, and there is little possibility that seizure will occur in the free ball bearing.

It is sectional drawing of the free ball bearing of one Example of this invention. It is the top view which showed the free ball bearing of FIG. 1 in the state which removed the cover body and the spherical body. It is the top view shown in the state except a small ball in FIG. It is AA sectional drawing of FIG. It is a principal part enlarged view of FIG. It is the perspective view which showed the free ball bearing of FIG. 1 in the state except the cover body. It is the perspective view shown in the state which excluded the spherical body in FIG. It is the perspective view shown in the state except the small ball in FIG. As an example of the usage mode of the free ball bearing of the present invention, a grooving device in a grooved metal tube manufacturing apparatus for manufacturing a grooved metal tube will be described. (A) is a side view of the grooving device 10; (A) is a front view (right arrow view) shown with the lid 16c of the housing 16 removed in (a), and (c) is a view showing only the free ball bearing 56 of (b). It is sectional drawing of the free ball bearing of the other Example of this invention. It is a figure at the time of using as a component of the bearing which shows the other example of the usage condition of the free ball bearing of this invention, and supports the rotating shaft of a large diameter.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for implementing a free ball bearing of the present invention will be described with reference to the drawings.

The free ball bearing of the present invention movably supports a moving body that moves in one direction. FIG. 1 is a sectional view of the free ball bearing 56 according to one embodiment, and FIG. 2 shows the free ball bearing 56 of FIG. 3 is a plan view showing a state in which the lid 54c and the sphere 55 are removed, FIG. 3 is a plan view showing the state in which the small sphere 80 is removed in FIG. 2, FIG. 4 is a cross-sectional view taken along line AA in FIG. It is a principal part enlarged view of FIG. 6 is a perspective view of the free ball bearing 56 of FIG. 1 with the lid 54c removed, and FIG. 7 is a perspective view of the free ball bearing 56 with the sphere 55 removed in FIG. FIG. 8 is a perspective view showing the state in which the small ball 80 is removed in FIG.
As shown in these drawings, the free ball bearing 56 includes one large sphere 55, a sphere holder 54 that accommodates the sphere 55 in a ball accommodating portion 54a that forms a concave spherical surface, and a concave spherical surface of the ball accommodating portion 54a. And a plurality of small spheres 80 on which the sphere 55 is placed. The spherical holder 54 includes a holder main body 54b having the ball accommodating portion 54a and a lid 54c that holds the spherical body 55.
In the ball housing portion 54a of the holder main body 54b, an even-numbered row forming the moving body moving direction is formed in the central region in the Y direction perpendicular to the moving body moving direction (arrow X direction in FIG. 2) of the concave spherical surface. A track groove is formed.
The even-numbered track grooves are composed of a plurality of pairs of a shallow groove 81a and a deep groove 81b, and the shallow groove 81a and the deep groove 81b in each pair are connecting passages 81c that are inclined surfaces at the ends thereof. The small sphere 80 can circulate between the shallow groove 81a and the deep groove 81b. A circulation path composed of the shallow groove 81a, the deep groove 81b, and the communication passage 81c is indicated by 81.
Each of the shallow groove 81a and the deep groove 81b is a groove having an arc cross section matched to the shape of the small ball 80, and the shallow groove 81a, the deep groove 81b, and the boundary wall are indicated by 82a. A boundary wall between a pair of the shallow groove 81a and the deep groove 81b is indicated by 82b.

In this embodiment, two sets of track grooves are formed on both sides of the center position in the direction orthogonal to the moving body moving direction, and the other areas in the concave spherical surface are simply concave spherical areas 83 without grooves. is there. A boundary wall between the grooved region and the grooveless region is indicated by 82c.
The depth of the shallow groove 81a is a depth in contact with the sphere 55, and the small sphere 80 in the shallow groove 81a rotates and moves while receiving a load while supporting the rotating sphere 55. The depth of the deep groove 81 b is a depth that does not contact the sphere 55 and is not subjected to a load from the sphere 55.
The diameter of the small sphere 80 in the embodiment is 4.0 mm, for example, with respect to the sphere 55 having a diameter of 40 mm. The gap h between the sphere 55 and the small sphere 80 in the deep groove 81b is 0.5 mm.

In the above-described free ball bearing 56, the sphere 55 of the free ball bearing 56 rotates in the same direction as the moving direction of the moving body with respect to the moving body moving in one direction.
Of the pair of track grooves of the shallow groove 81a and the deep groove 81b in the central region, the small sphere 80 in the shallow groove 81a is in contact with the sphere 55 and receives a load on the sphere 55. It rotates in the direction opposite to the direction of rotation (the direction opposite to the moving direction of the moving body). On the other hand, the small sphere 80 in the deep groove 81b is not in contact with the sphere 55 and is in an unloaded state.
Since the track groove forms the moving body moving direction, the small ball 80 in the shallow groove 81a moves in the shallow groove 81a in the direction opposite to the moving direction of the moving body while rotating, and passes through the connecting passage 81c at the end thereof. Then, it enters the adjacent deep groove 81b. The small sphere 80 entering the deep groove 81b pushes the small sphere 80 in the deep groove 81b, and the small sphere 80 in the deep groove 81b moves in the deep groove 81b in the moving body moving direction (forward direction). It enters the shallow groove 81a through the communication passage 81c. The small sphere 80 entering the shallow groove 81a from the deep groove 81b rotates in the direction opposite to the rotation direction of the sphere 55 (the direction opposite to the moving direction of the moving body) while receiving a load by contacting the sphere 55 as described above. .
Thus, the small sphere 80 circulating between the shallow groove 81a and the deep groove 81b supports the rotation of the sphere 55 while rotating in the reverse direction when in the shallow groove 81a.
Since the groove direction of the track groove coincides with the moving body moving direction, the small sphere 80 in the shallow groove 81a supporting the sphere 55 rotating in the moving body moving direction is substantially parallel to the rotation axis of the rotating sphere 55. Rotate in a manner with a rotation axis (reverse direction but rotate in roughly the same direction). Therefore, there is little unnecessary slip between the sphere 55 and the small sphere 80, and the frictional resistance between the sphere 55 and the small sphere 80 is remarkably small. (
Since the frictional resistance against the rotation of the sphere 55 can be reduced as described above, the power for driving the moving body can be reduced as much as possible. In addition, the occurrence of seizure of the free ball bearing can be prevented as much as possible.
Therefore, a free ball bearing for supporting a moving body moving in one direction is rotated at an extremely high speed, for an application where the sphere 55 needs to be rotated at a very high speed, or an extremely large load must be borne. In addition, when used in applications where it is necessary to bear an extremely large load, it has been effective for minimizing the power for driving the moving body or for preventing the free ball bearing from being seized.

FIG. 9 shows an example of the use of the free ball bearing 56 of the present invention. For example, a square metal tube 8 ″ that is installed downstream of a sizing roll stand in an electric sewing tube manufacturing apparatus and is continuously driven and driven. On the other hand, it is a figure explaining the case where it uses for the grooving apparatus 10 which forms a concave groove in the four surfaces.
This grooving device 10 includes a rolling adjustment mechanism 57 and four ball outside mechanisms 19 provided with a free ball bearing 56 spaced apart in the circumferential direction in a mode in which the spherical body 55 pushes the pipe outer surface, and a cross section along the pipe inner surface. A core 20 which is formed in a short rod-like shape and is disposed in the pipe at a position corresponding to the pipe outside mechanism 19 in the longitudinal direction of the pipe, and in the example shown in FIG. In the housing 16.
The reduction adjusting mechanism 57 adjusts the reduction of the sphere 55 by adjusting the position of the free ball bearing 56 (position of the sphere 55). In this grooving device 10, when the metal tube 8 ″ before grooving is driven in the direction of the arrow in FIG. 9 (a), the tube wall has an outer surface including the spherical body 55 and the groove-shaped recess 20 a of the core 20. In this grooving process, the spherical body 55 of the free ball bearing 56 receives a significantly large load at a high speed. Although rotating, the frictional resistance between the small sphere 80 and the sphere 55 was small, and there was no occurrence of seizure or the like, and it was able to withstand such a use environment.
1 to 8 is different from the shape of the holder main body 54b in the free ball bearing 56 shown in FIG. 9 in the shape of the lower surface portion of the holder main body 54b in the free ball bearing 56 shown in FIGS. However, either may be used.

FIG. 10 shows a free ball bearing 56 'according to another embodiment of the present invention.
In this free ball bearing 56 ', the even-numbered track grooves of the concave spherical surface of the holder body 54 are only in the central region in the left-right direction (Y direction) orthogonal to the moving body moving direction, and the region 54d on the outer side in the left-right direction is It is a simple concave spherical surface that is directly along the surface of the sphere 55.
In the region 54d on the laterally outer side of the central region, even if the sphere 55 is in direct contact with the simple concave spherical surface without any small spheres, a large load does not act on the concave spherical surface, so the frictional resistance is small, Sometimes it doesn't matter too much. In such a case, the structure as shown in FIG. 10 yielded a free ball bearing that was easy to manufacture without degrading performance.

The free ball bearing of the present invention is, for example, as a free ball bearing 56 as a single component that constitutes a bearing 91 with a plurality of spaces arranged around the rotating shaft 90 having a large diameter as shown in FIG. Can also be applied.
That is, the moving body that moves in one direction in the present invention is not limited to a moving body that moves in the center of gravity position like the metal tube in the above-described embodiment, but a rotating shaft that rotates without moving the center of gravity position ( Including the case of a rotating body). The moving body moving direction in this case refers to the moving direction of each point on the outer peripheral surface of the rotating shaft 90, and each point on the outer peripheral surface of the rotating shaft 90 moves in one direction with respect to the sphere of the free ball bearing 56.

8 Grooved metal tube 10 Grooving device 19 External mechanism 20 Core 20a Groove-shaped concave portion 54 Spherical holder 54a Ball housing portion (concave spherical surface)
54b Holder body 54c Lid 55 Ball 56 Free ball bearing 57 Reduction mechanism 80 Small ball 81 Circulation path (shallow groove and deep groove and communication path)
81a Shallow groove 81b Deep groove 81c Connecting passage 82a Shallow groove, deep groove and boundary wall 82b Boundary wall 82c between a pair of shallow groove and deep groove Boundary wall 83 between grooved area and grooveless area 83 Simple groove without groove Spherical region 90 Rotating shaft 91 Bearing

Claims (3)

A plurality of small spheres are arranged on the concave spherical surface of a spherical holder having a ball receiving portion forming a concave spherical surface, and have one large sphere rotatably supported by the plurality of small spheres. A free ball bearing that movably supports a moving body that moves in one direction,
The even-numbered track grooves forming the moving body moving direction are formed in at least the central region in the left-right direction orthogonal to the moving body moving direction of the concave spherical surface of the ball housing portion, and the even-numbered track grooves are shallow grooves and deep grooves. And the shallow groove and the deep groove in each pair communicate with each other through a communication passage connecting both ends, and the small sphere in the central region is a shallow groove. A free ball bearing characterized in that it can circulate between deep grooves.   The sphere holder includes a holder main body having the ball accommodating portion and accommodating the plurality of small spheres and one sphere, and the sphere holder is attached to an upper surface of the holder main body so that a part of the sphere is exposed. The free ball bearing according to claim 1, further comprising a lid for pressing. The even-numbered track grooves of the concave spherical surface of the holder body are only in the central region in the left-right direction orthogonal to the moving body moving direction, and the outer region in the left-right direction is a concave spherical surface that directly follows the surface of the sphere. The free ball bearing according to claim 2.