JP2011117593A - Limited stroke motion guide apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a limited stroke motion guide apparatus that can be compact without sacrificing the stroke of a movable member relative to a stationary member and the capacity of load bearing. <P>SOLUTION: In the limited stroke motion guide apparatus having the stationary member having a rolling surface for rolling elements, the movable member having a rolling surface for rolling elements in the position opposite to the rolling surface of the stationary member and assembled with the stationary member via many rolling elements rolling on the rolling surfaces, and a rolling element cage disposed between the stationary member and the movable member to align the rolling elements, the rolling element cage has an oblong rolling element holding hole accommodating a rotatable set of rolling elements rolling on the same rolling surface. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  In the present invention, a rolling element cage in which rolling elements such as balls and rollers are arranged between a fixed side member and a moving side member is arranged, and the moving side member moves relative to the fixed side member as the rolling element cage moves. The present invention relates to a finite stroke type motion guide device that reciprocates.

  Of the motion guide devices that support the linear movement of a movable body such as a table in various industrial machines, a finite stroke type device using a rolling element cage is known as a device for light load applications. The finite stroke type motion guide device includes, for example, a fixed side member in which a ball rolling groove is formed, and a moving side member having a ball rolling groove at a position facing the rolling groove of the fixed side member. And a large number of balls rolling while applying a load between the fixed side member and the moving side member, and a thin plate-like rolling element cage interposed in a gap between the fixed side member and the moving side member. ing.

  For example, in the finite stroke type motion guide device disclosed in Japanese Patent Application Laid-Open No. 11-201158, the stationary member is formed in a channel shape, while the moving member is formed in a channel shape that is slightly smaller than the stationary member. A rolling element cage obtained by pressing a thin metal plate is disposed between the fixed member and the movable member. In addition, a cylindrical rolling element cage in which the fixed side member is formed in a cylindrical shape, while the moving side member is formed as a shaft passing through the fixed side member, and is formed from a resin between them. There is also an example in which is arranged.

  In any case, the conventional rolling element cage has a plurality of holding holes arranged to hold the individual balls in a rotatable manner so that the individual balls are individually accommodated in the holding holes. It has become. Each holding hole penetrates between the inner peripheral surface and the outer peripheral surface of the rolling element cage. Thereby, the ball | bowl currently hold | maintained at each holding | maintenance hole can come in contact with the rolling groove | channel of a fixed side member and a movement side member.

  The length of the rolling element cage in the moving direction is shorter than the length of the fixed side member and the rolling groove of the moving side member. When the moving side member is moved relative to the fixed side member, the rolling of the ball is reduced. The rolling element cage is configured to move in the rolling direction of the ball through the gap between the moving side member and the fixed side member as it runs. For this reason, stopper members are provided on both front and rear end surfaces in the moving direction of the moving side member, so that the rolling element cage that has moved along with the rolling of the ball is released from the gap between the moving side member and the fixed side member. It is preventing.

Japanese Patent Laid-Open No. 11-201158

  However, in such a conventional finite stroke type motion guide device, a plurality of holding holes for independently accommodating individual balls are provided in the rolling element cage, and the holding holes adjacent to each other are separated. Therefore, the distance between the centers of the balls must be larger than the ball diameter. On the other hand, the size of the rolling element cage must be restricted by the length of the rolling groove in the fixed member and the moving member, and the required stroke amount of the moving member. For this reason, in the rolling element cage which accommodates a ball | bowl separately, there existed a subject that the number of balls which roll the same rolling groove cannot be set so much. In particular, when downsizing the motion guide device, if the ball diameter is set to be small for miniaturization, the same amount of load cannot be applied unless the number of balls is increased accordingly. Such a conventional rolling element cage is an obstacle to miniaturization of the motion guide device.

  The present invention has been made in view of such problems, and the object of the present invention is to achieve downsizing without sacrificing the stroke amount of the moving side member relative to the fixed side member or the load carrying capacity of the load. It is an object of the present invention to provide a finite stroke type motion guide device capable of performing the above.

  That is, the present invention has a fixed side member having a rolling surface of the rolling element, and a large number of rolling members that have the rolling surface of the rolling element at a position facing the rolling surface of the fixed side member and roll on the rolling surface. A movable member assembled to the stationary member via the rolling member, and a rolling member cage disposed between the stationary member and the movable member to align the rolling members. In the stroke type motion guide device, the rolling element cage has a long hole-shaped rolling element holding hole in which a plurality of rolling elements that roll on the same rolling surface are accommodated rotatably. Is provided.

  According to the present invention configured as described above, the rolling element cage is provided with the elongated hole-shaped rolling element holding hole, and the rolling element holding hole includes a plurality of rolling elements that roll on the same rolling surface. Since the rolling elements are rotatably accommodated as a set, the rolling elements in the moving direction of the rolling element cage can be compared with the conventional rolling element cage that is accommodated in the rolling element holding hole in an independent state. If the lengths are the same, the number of rolling elements arranged in the rolling element cage can be increased. As a result, while reducing the diameter of the rolling elements, it is possible to avoid a decrease in load capacity by increasing the number of rolling elements to be used. By reducing the diameter of the rolling elements, the motion guide device It is possible to achieve downsizing.

It is a half section side view showing a first embodiment of a finite stroke type motion guide device to which the present invention is applied. It is a perspective view which shows the rolling element cage of the exercise | movement guide apparatus shown in FIG. It is an expanded sectional view which shows the contact state with respect to the spline shaft and nut member of a ball | bowl. It is a perspective view which shows 2nd embodiment of the motion guide apparatus of the finite stroke type to which this invention is applied. It is front sectional drawing of the exercise | movement guide apparatus shown in FIG. It is a perspective view which shows the ball cage with which the exercise | movement guide apparatus shown in FIG. 4 is provided.

  Hereinafter, the finite stroke type motion guide apparatus of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 shows a finite stroke ball spline apparatus 1 to which the present invention is applied. The ball spline device 1 uses a ball 2 as a rolling element, a spline shaft 3 in which a rolling groove 30 of the ball 2 is formed along the longitudinal direction, and the spline shaft 3 via a number of balls 2. And a ball cage 5 disposed between the spline shaft 3 and the nut member 4 as a rolling element cage for aligning the balls 2 in a predetermined state. ing. When the ball 2 rolls between the spline shaft 3 and the nut member 4, the nut member 4 can move freely in the axial direction with respect to the spline shaft 3.

  However, the movement of the nut member 4 relative to the spline shaft 3 is relative. When the ball spline device 1 is used, the nut member 4 is moved relative to the fixed spline shaft 3 or is fixed. The spline shaft 3 may be moved with respect to the nut member 4. Therefore, either the spline shaft 3 or the nut member 4 corresponds to the stationary member of the present invention, and the other corresponds to the moving member of the present invention.

  The spline shaft 3 is formed in a substantially circular cross section, and two rolling grooves 30 are formed on the outer peripheral surface thereof. These rolling grooves 30 are provided at equal intervals so as to bisect the outer peripheral surface of the spline shaft 3 in the circumferential direction. On the other hand, the nut member 4 has a hollow portion and is formed in a substantially cylindrical shape, and the spline shaft 3 passes through the hollow portion. The ball rolling groove 40 is formed on the inner peripheral surface of the hollow portion at a position facing the rolling groove 30 of the spline shaft 3. As shown in FIG. They are arranged so as to be sandwiched between the running groove 30 and the rolling groove 40 of the nut member 4. Therefore, when the nut member 4 is moved in the axial direction with respect to the spline shaft 3, the ball 2 rolls on the rolling groove 30 of the spline shaft 3 and the rolling groove 40 of the nut member 4. The rolling groove 30 of the spline shaft 3 and the rolling groove 40 of the nut member 4 correspond to the rolling surface of the rolling element in the present invention.

  The rolling groove 30 of the spline shaft 3 has a cross section perpendicular to the longitudinal direction formed in a Gothic arch shape. The Gothic arched rolling groove 30 is formed by two arcuate curved surfaces intersecting at an angle of approximately 90 °, and the ball 2 is in contact with the rolling groove 30 at two points. Similarly, the rolling groove 40 formed in the nut member 4 has a cross section perpendicular to the longitudinal direction formed in a Gothic arch shape. The shapes of the rolling groove 30 of the spline shaft 3 and the rolling groove 40 of the nut member 4 are not necessarily formed in a Gothic arch shape, and may be, for example, a circular arc formed of a single arcuate curved surface. Absent.

  As shown in FIG. 2, the ball cage 5 is formed in a substantially cylindrical shape, and its inner diameter is set slightly larger than the outer diameter of the spline shaft 3, while the outer diameter is a hollow portion of the nut member 4. Is set to be slightly smaller than the inner diameter. That is, the ball cage 5 is arranged in the gap between the spline shaft 3 and the nut member 4.

  In order to prevent the ball cage 5 from slipping out between the spline shaft 3 and the nut member 4, a gap between the nut member 4 and the spline shaft 3 is provided at both ends in the axial direction of the nut member 4 as shown in FIG. 1. Stopper members 40 and 41 are provided to close the door. One stopper member 40 is provided integrally with the nut member 4, while the other stopper member 41 is a nut member after the ball cage 5 is inserted so that the ball cage 5 can be inserted into the hollow portion of the nut member 4. 4 is fixed. Further, the inner peripheral edges of these stopper members 40 and 41 are opposed to the spline shaft 3 leaving a slight gap, and also function to prevent dust from entering the inside of the nut member 4 from the outside.

  As shown in FIG. 2, the ball cage 5 is formed with rolling element holding holes 50 for accommodating the balls 2. Such rolling element holding holes 50 are provided at positions facing the rolling grooves 30 of the spline shaft 3, and two rolling element holding holes 50 are arranged in series with respect to one rolling groove 30. Each rolling element holding hole is formed in a long hole shape parallel to the rolling groove 30, and a plurality of balls rolling on the same rolling groove 30 are accommodated together in one rolling element holding hole. It has become so.

  The length of the rolling element holding hole 50 along the moving direction of the ball cage 5 is substantially the same as (diameter of the ball 2) × (number of balls 2 accommodated) or slightly larger than that, The plurality of balls 2 accommodated in the same rolling element holding hole 50 are close to each other and roll in the rolling groove 30 of the spline shaft 3 without being separated. Therefore, the moving distance of the ball cage 5 with respect to the spline shaft 3 or the nut member 4 substantially matches the rolling distance of the ball 2 with respect to the spline shaft 3 or the nut member 4.

  In the example shown in FIG. 1, eight balls 2 are arranged in a single rolling groove 30, and these balls 2 are divided and accommodated in two rolling element holding holes 50. Accordingly, four balls 2 are accommodated in one rolling element holding hole 50. However, the number of the rolling element holding holes 50 facing one rolling groove 30 is one, and it is possible to accommodate all eight balls 2 in the rolling element holding holes 50. In this way, the number of rolling element holding holes 50 facing one rolling groove 30 is one, and all balls 2 rolling in the same rolling groove 30 with respect to the rolling element holding holes 50 are accommodated. By doing so, it becomes possible to arrange more balls 2 with respect to the ball cage 5 and to increase the load carrying capacity of the ball spline device 1.

  However, in that case, a single rolling element holding hole 50 exists over substantially the entire length of the ball cage 5 in the moving direction, and the ball cage 5 and the ball 2 associated with the deformation of the rolling element holding hole 50 There is concern about interference. Therefore, in the ball cage 5 shown in FIG. 2, the balls 2 rolling on one rolling groove 30 are divided into two groups, and a rolling element holding hole 50 is provided for each group. If comprised in this way, since the wall 51 which partitions a pair of rolling element holding hole 50 in the approximate center of the longitudinal direction of the ball cage 5 will exist, a deformation | transformation of the ball cage 5 will be suppressed and rolling element holding hole 50 of Interference between the inner peripheral wall and the ball 2 can be suppressed.

  As shown in FIG. 3, the rolling element holding hole 50 of the ball cage 5 is set so that the opening width on the spline shaft 3 side is slightly smaller than the diameter of the ball 2, and the spline shaft 3 is connected to the nut member 4. The ball 2 is configured not to come out of the rolling element holding hole 50 even if it is pulled out.

  Therefore, in assembling the ball spline device 1, first, the ball cage 5 in which the balls 2 are arranged in the rolling element holding holes 50 is inserted into the hollow portion of the nut member 4, and then the stopper member 41 is inserted into the nut member 4. The ball cage 5 is sealed in the hollow portion of the nut member 4. The ball cage 5 can freely reciprocate between one stopper member 40 and the other stopper member 41 in the hollow portion of the nut member 4, but the rolling element holding hole 50 of the ball cage 5 is formed by the spline shaft 3. Since the opening width on the side is set to be smaller than the diameter of the ball 2, the ball 2 does not fall out of the rolling element holding hole 50. Then, by inserting the spline shaft 3 into the hollow portion of the ball cage 5, the ball spline device 1 is completed.

  When the ball cage 5 is in contact with one stopper member 40 and the spline shaft 3 is moved in the axial direction with respect to the nut member 4, the balls 2 arranged in the ball cage 5 are moved to the nut member 4 and the spline shaft 3. And the ball cage 5 moves toward the other stopper member 41. The spline shaft 3 can be moved until the ball cage 5 abuts against the stopper member 41. The moving distance of the spline shaft 3 at this time is twice the moving distance of the ball cage 5.

  Therefore, when the axial length of the nut member 4 is limited and the required stroke amount in the axial direction of the spline shaft 3 is determined, the axial length of the ball cage 5 is naturally limited. End up. On the other hand, in order to secure sufficient load carrying capacity while reducing the diameter of the ball 2 as the diameter of the nut member 4 is reduced, it is necessary to increase the number of balls 2 arranged in the ball cage 5.

  In the above-described ball spline device 1 to which the present invention is applied, a long hole-shaped rolling element holding hole 50 is formed in the ball cage 5, and a plurality of balls 2 rolling in the same rolling groove 30 are rolled. Since the ball cages 5 are arranged together in the moving body holding holes 50, the conventional ball cage in which independent rolling body holding holes are provided for the individual balls 2 if the ball cages 5 have the same axial length. It is possible to arrange a larger number of balls 2 than in FIG. As a result, it is possible to reduce the diameter of the ball 2 and, in turn, to reduce the diameter of the nut member 4 while ensuring a load capacity equal to or higher than that of the conventional one, and the ball spline device 1 can be reduced in size. did it.

  4 and 5 show a finite stroke type slide rail unit to which the present invention is applied. The slide rail unit includes an outer rail 110 as a fixed side member, an inner rail 120 as a moving side member housed in the outer rail 110, and rolling elements that roll between the outer rail 110 and the inner rail 120. And a ball cage 140 as a rolling element cage in which a large number of balls 130 are arranged at a predetermined interval between the outer rail 110 and the inner rail 120.

  The outer rail 110 is formed by precision forming a steel plate by roll forming, and is formed into a channel shape by bending a pair of ball rolling portions 112 and 112 along the longitudinal direction of the attachment portion 111. A ball rolling surface 113 having a curvature approximate to the spherical surface of the ball 130 is formed on the inner side surface of the ball rolling portion 112.

  On the other hand, the inner rail 120 is similarly formed from a steel plate, and is formed in a channel shape by bending the pair of ball rolling portions 122 and 122 along the longitudinal direction of the mounting portion 121. However, since the inner rail 120 is accommodated between the ball rolling portions 112 and 112 of the outer rail 110 and the balls 130 are arranged between the inner rail 120 and the outer rail 110, the inner rail 120 is formed to be slightly smaller than the outer rail 110 and A ball rolling surface 123 is formed on the outer surface of the rolling portion 122.

  The mounting portions 111 and 121 of the rails 110 and 120 are respectively provided with screw holes 114 and 124 through which the mounting screws 150 pass. For example, the outer rail 110 uses the mounting screws 150 as shown in FIG. 200, the inner rail 120 is fixed to the drawer 201 using the mounting screw 150, respectively.

  FIG. 6 is a perspective view showing the ball cage 140. The ball cage 140 is formed by pressing a steel plate or by injecting a synthetic resin into a mold. The ball cage 140 is inserted between the outer rail 110 and the inner rail 120 so that a gap between the rails 110 and 120 is formed. A number of rolling balls 130 are aligned at equal intervals. In FIG. 6, a part of the ball cage 140 is omitted for easy understanding.

  The ball cage 140 is formed with rolling element holding holes 141 for accommodating the balls 130. The rolling element holding holes 141 are provided at positions facing the ball rolling surface 113 of the outer rail 110 and the ball rolling surface 123 of the inner rail 120, and the ball rolling surface 113 and the inner rail 120 of the outer rail 110 are arranged. It is formed in a long hole shape parallel to the ball rolling surface 123. In the rolling element holding hole 141 configured as described above, a plurality of balls 130 rolling on the ball rolling surface 113 of the outer rail 110 and the ball rolling surface 123 of the inner rail 120 are provided as one rolling element holding hole 141. Are to be housed together.

  The length of the rolling element holding hole 141 along the moving direction of the ball cage 140 is substantially the same as (diameter of the ball 130) × (number of balls 130 accommodated) or slightly larger than that. The plurality of balls 130 accommodated in the same rolling element holding hole 141 come close to each other and roll on the ball rolling surface 113 of the outer rail 110 and the ball rolling surface 123 of the inner rail 120 without being separated. ing. Therefore, the moving distance of the ball cage 140 with respect to the outer rail 110 or the inner rail 120 substantially matches the rolling distance of the ball 130 with respect to the outer rail 110 or the inner rail 120.

  In the slide rail unit shown in FIG. 4, 20 balls 130 are arranged on the ball rolling surface 113 of the outer rail 110 and the ball rolling surface 123 of the inner rail 120, and these balls 130 are placed in the rolling element holding holes. 141. However, the number of the rolling element holding holes 141 facing the ball rolling surface 113 of the outer rail 110 and the rolling surface 123 of the inner rail 120 is plural, and the ball rolling surface 113 of the outer rail 110 and the rolling surface of the inner rail 120 are set. It is also possible to divide the balls 130 rolling on 123 into groups and to provide rolling element holding holes 141 for each group.

  In the slide rail unit to which the present invention is configured as described above, since the outer rail 110 and the inner rail 120 are fitted via the ball 130, the outer rail 110 is rolled by the rolling of the ball 130. The inner rail 120 accommodated in the inner rail 120 can be smoothly pulled out from the outer rail 110.

  This slide rail unit is configured to have the shortest overall length when the inner rail 120 is completely overlapped with the outer rail 110, that is, when the inner rail 120 is completely pulled into the outer rail 110. The state in which the drawer 201 is completely stored in the furniture body 200 corresponds to this state.

  According to the slide rail unit to which the present invention configured as described above is applied, a long hole-shaped rolling element holding hole 141 is formed in the ball cage 140 and rolls on the same rolling surfaces 113 and 123. Since the plurality of balls 130 are arranged together in the rolling element holding holes 141, if the axial length of the ball cage 140 is the same, independent rolling element holding holes are provided for the individual balls 130. More balls 130 can be arranged as compared with the conventional ball cage provided. As a result, it is possible to reduce the diameter of the ball 130 and, in turn, to reduce the diameter of the outer rail 110 and the inner rail 120 while ensuring a load capacity equal to or greater than that of the conventional one, thereby achieving a reduction in the size of the slide rail unit. It becomes possible.

  In the first embodiment described above, the present invention is applied to a ball spline device. In the second embodiment, the present invention is applied to a slide rail unit. However, the present invention is not limited thereto. For example, a linear guide device in which a ball cage is interposed between a pair of bearing races that perform relative reciprocating motion, and a ball cage is interposed between a round shaft and a nut member that performs relative motion relative thereto. It can be applied to a linear bushing device or the like.

  Further, the rolling elements are not limited to balls, and rollers may be used. In that case, the cross-sectional shape of the rolling surface of the rolling element may be a curved rolling groove similar to the case of the ball, or may be a simple planar rolling surface, depending on the shape of the roller used.

  DESCRIPTION OF SYMBOLS 1 ... Ball spline apparatus, 2 ... Ball 130 ... Spline shaft, 4 ... Nut member, 5 ... Ball cage, 50 ... Rolling body holding hole

Claims (3)

A fixed side member having a rolling surface of the rolling element, and a plurality of rolling elements that have the rolling surface of the rolling element at a position facing the rolling surface of the fixed side member and roll on the rolling surface. In a finite stroke type motion guide device comprising: a moving side member assembled to the fixed side member; and a rolling element cage arranged between the fixed side member and the moving side member to align the rolling elements. ,
The rolling element cage is provided with a long hole-shaped rolling element holding hole in which a plurality of rolling elements that roll on the same rolling surface are accommodated rotatably. A finite stroke type motion guide device. The finite stroke type motion guide device according to claim 1, wherein the length of the rolling element holding hole in the direction parallel to the rolling surface corresponds to the number of rolling elements accommodated in the rolling element holding hole. . The finite stroke type motion guide device according to claim 2, wherein a plurality of rolling element holding holes are provided for one rolling surface.

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