JP2012255499A - Multi-row combination ball bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multi-row combination ball bearing, in which defects such as damage to or breaking of the bearing ring can be prevented even when an extremely large thrust load is applied.SOLUTION: The multi-row combination ball bearing 10 includes at least two rows of combination ball bearings 11A, 11B in a parallel assembly, and a counterbore 12d is formed in a groove shoulder 12c of an outer ring 12 of each ball bearing 11A, 11B. The dimensions of the inner and outer diameters and the width dimension of the ball bearing 11A, 11B correspond to an ISO-standard bearing. The extended lines La, Lb of each line connecting from the ball center O of the ball bearing 11A on the left to each of radial both end points a, b of the contact ellipse C in an outer ring raceway groove 12a pass through the outer peripheral surface of the outer ring 12 of the ball bearing 11A and the plane 12e of the axial end of the outer ring 12 of the ball bearing 11B on the right adjacent to the ball bearing 11A on axial one side. Further, the extended lines La, Lb of each line connecting from the ball center O of the ball bearing 11B on the right to each of radial both end points a, b of the contact ellipse C in an inner ring raceway groove 13a pass through the inner peripheral surface of an inner ring 13 of the ball bearing 11A on the right and the plane 13e of the axial end of an inner ring 13 of the ball bearing 11A on the left.

Description

  The present invention relates to a multi-row combination ball bearing, and in particular, an application in which a thrust load larger than a radial load is applied, for example, a ball screw support rolling bearing for an electric injection molding machine, or a ball screw support rolling bearing for a die casting machine, The present invention relates to a multi-row combination ball bearing that is applied to applications that rotate under a large load in the axial direction, such as a ball screw support rolling bearing for a servo press machine.

  As a method for producing a plastic product, a method by injection molding is common. In the case of injection molding, when the molding material is a thermoplastic resin such as polyamide (PA), polyphenylene sulfide (PPS), or polyether ether ketone (PEEK), injection is performed on plastic (usually 180 to 450 ° C) heated to a softening temperature. Apply pressure to fill the mold and mold. In this molding process, it is necessary to maintain the internal pressure of the mold until the plastic filled in the mold is solidified, which is called “clamping”.

  In the conventional mold clamping of an injection molding machine, a cylinder driving system by hydraulic control has been mainly used as a method for giving a mold clamping force. However, recently, a ball screw drive system based on electric servo control using a high torque motor that does not use a large amount of oil and is environmentally friendly and excellent in energy saving has been developed and put into practical use.

  4 and 5 show an electric injection molding machine 101, which includes a mold clamping unit 102 and an injection unit 103. FIG. The mold clamping unit 102 includes a rear platen 104, a movable platen 105, and a fixed platen 106, and a mold clamping mechanism 108 in which a mold 107 disposed between the movable platen 105 and the fixed platen 106 is disposed between the rear platen 104 and the movable platen 105. To open / close and close the mold.

  The mold clamping mechanism 108 has a toggle structure, and when the mold clamping ball screw 110 pivotally supported on the rear platen 104 is driven and rotated by the mold clamping motor 109, the cross head 111 moves back and forth and expands and contracts. As a result, the movable platen 105 is moved back and forth. The mold clamping ball screw 110 is pivotally supported on the rear platen 104 by a support bearing 112.

  Further, the movable platen 105 is provided with a drive mechanism 141 that operates an ejector pin 140 for projecting a molded product from the mold 107. The drive mechanism 141 includes a motor and a ball screw, and moves the ejector pin 140 by rotating an ejector shaft 142 that forms a screw shaft of the ball screw. The ejector shaft ball screw is pivotally supported on the movable platen 105 by a support bearing (not shown).

  The injection unit 103 includes a rear plate 113, a movable plate 114, and a front plate 115. The base of the metering / injecting screw 117 disposed in the cylinder assembly 116 of the front plate 115 is the front surface of the movable plate 114 (on the mold clamping unit side). ) Through a support bearing 118 (screw sleeve). The metering / injecting screw 117 is driven and rotated by a metering motor (not shown) attached to the movable plate 114 when the resin for molding is weighed, melted and kneaded.

  As shown in FIG. 5, a ball nut 120 is fixed to the rear surface of the movable plate 114, and an injection ball screw 121 screwed to the movable nut 114 is pivotally supported by the rear plate 113, and the injection mechanism 122. Is configured. The injection ball screw 121 is pivotally supported on the rear plate 113 by a support bearing 123 and is driven by an injection motor 124 attached to the rear plate 113.

  When the injection motor 124 is driven in the forward direction, the injection ball screw 121 is rotated forward, the movable plate 114 moves forward, and the molten resin in the cylinder assembly 116 is injected into the mold 107 by the injection / metering screw 117. Is done. After the injection, the metering motor is driven, the injection / metering screw 117 is rotated, and the resin is newly metered and kneaded. At this time, the injection / metering screw 117 is pushed back by the pressure of the resin to be fed, but back pressure is applied by the injection motor 124 so that kneading and melting are sufficiently performed. At the stage where the metering is completed, in order to prevent leakage from the tip of the nozzle, the injection motor 124 is reversed, the injection / metering screw 117 is slightly retracted, and suck back is performed.

  Further, the injection unit 103 is provided with a nozzle touch mechanism 153 that rotates the ball screw 151 forward or backward by the driving motor 150 to move the cylinder assembly 116 forward and backward on the fixed platen 106. The nozzle touch mechanism 153 presses the nozzle 116 a at the tip attached to the cylinder assembly 116 against the mold 107 attached to the fixed platen 106 with a predetermined force. The nozzle touch ball screw 151 is pivotally supported by a support bearing (not shown).

  Here, in the injection molding machine by electric servo control, in the above-described ball screw support bearing 112 for clamping, ball screw support bearing for ejector shaft, ball screw support bearing 123 for injection, and ball screw support bearing for nozzle touch, In order to apply a large axial load at the time of rotational support and mold clamping, a special dedicated ball screw support bearing using a large-diameter ball as shown in FIG. 6 has begun to be used.

  Further, in the ball screw device described in Patent Document 1, in a multi-row combination ball bearing that supports a screw shaft of a ball screw applied to an electric injection molding machine, a contact angle is set to 40 degrees or more and 65 degrees or less, and a thrust load is reduced. It is described that a large load capacity is secured.

JP 2008-101711 A

  By the way, in the ball screw support portion applied to each axis of the injection molding machine, a standard as shown in FIG. 6, which is mainly used for a headstock of a machine tool or a bed feeding mechanism for mounting a workpiece. An angular ball bearing 200 for supporting a ball screw is used. In such an angular ball bearing 200, the contact angle is matched to the load direction as much as possible so that the rolling fatigue life of the bearing can be satisfied even when the axial load of the ball screw generated by the cutting load during machining is applied. Usually, the contact angle is set to 60 degrees. In the case of a parallel combination in which bearings having the same contact angle direction are used next to each other, extension lines La and Lb of lines connecting the end points a and b of the contact ellipse C in the raceway grooves from the center of the ball are provided. Normally, it was not included in the axial end plane 201 of the adjacent bearing 200. Such angular contact ball bearings are designed in consideration of the rolling fatigue life, and in the case of machine tool applications, such an extremely large load that the bearing ring is damaged by bending is not applied. Even if specified in combination, there was no problem.

  On the other hand, as hydraulic injection molding machines and the like have been electrified, there has been an application for applying a large thrust load, which has not been assumed in the conventional ball screw support angular contact ball bearings. For this reason, when a large thrust load is applied, an excessive load is applied to the groove portion of the bearing ring, which may cause problems such as cracking of the bearing ring.

  In addition, in the application of an injection molding machine, in order to satisfy the fatigue life of a bearing with respect to a large load, a multi-row combination of 4 to 5 rows, which has been hardly adopted so far, is applied so that a load in one direction can be applied. In many cases, there are many places where malfunctions are expected.

  The present invention has been made in view of the above-described problems, and the object thereof is to prevent problems such as breakage and cracking of the race ring even when a very large thrust load is applied. The object is to provide a multi-row combination ball bearing.

The above object of the present invention can be achieved by the following constitution.
(1) In a multi-row combination ball bearing comprising at least two rows of ball bearings in parallel combination and having a counter bore formed in at least one groove shoulder of the outer ring and inner ring of each ball bearing,
The ball bearings correspond to ISO standard bearings whose inner and outer diameters and widths are
Between the adjacent ball bearings of the parallel combination, an outer ring spacer and an inner ring spacer are arranged,
Of the adjacent ball bearings of the parallel combination, the extension line of each line connecting the radial end points of the contact ellipse in the outer ring raceway groove from the ball center of one of the ball bearings is the axial end plane of the outer ring spacer And an extension line of each line connecting the radial center ends of the contact ellipse in the inner ring raceway groove from the ball center of the other ball bearing passes through the axial end plane of the inner ring spacer. Multi-row combination ball bearing.
(2) When the adjacent ball bearings of the parallel combination are arranged without the outer ring and the inner ring spacer, each line connecting the radial center ends of the contact ellipse in the outer ring raceway groove from the ball center of the one ball bearing The extension of each line connecting at least one of the radial ends of the contact ellipse in the inner ring raceway groove from the ball center of the other ball bearing does not intersect with the axial end plane of the other ball bearing. The multi-row combination ball bearing according to (1), wherein at least one of the wires does not intersect an axial end plane of the one ball bearing.
(3) At least three rows of the ball bearings are arranged in parallel through the outer ring spacer and the inner ring spacer, respectively.
Among the ball bearings of the parallel combination, an extension line of each line connecting the radial center ends of the contact ellipse in the outer ring raceway groove from the ball center of the ball bearing located in the middle in the axial direction is adjacent on the one side in the axial direction. An extension line of each line passing through the axial end plane of the outer ring spacer and connecting the radial center of the contact ellipse in the inner ring raceway groove from the ball center of the ball bearing located in the middle of the axial direction is the other side in the axial direction. The multi-row combination ball bearing according to (1) or (2), wherein the multi-row combination ball bearing according to (1) or (2) passes through an axial end plane of the adjacent inner ring spacer.

  According to the multi-row combination ball bearing of the present invention, the ball bearing corresponds to a standard bearing having inner and outer diameters and width dimensions, and from the ball center of one of the adjacent ball bearings in parallel combination. The extension line of each line connecting the radial end points of the contact ellipse in the outer ring raceway groove passes through the axial end plane of the outer ring spacer, and the diameter of the contact ellipse in the inner ring raceway groove from the ball center of the other ball bearing. The extension line of each line connecting the direction end points passes through the axial end plane of the inner ring spacer. With such a configuration, when a very large thrust load is applied to the bearing, the load in the contact angle direction generated between the contact portions between the rolling elements and the raceway grooves of the inner and outer rings is applied only to the inner and outer rings of the bearing. Without this, the load can be backed up by the outer ring spacer and the inner ring spacer. As a result, the load can be backed up in adjacent bearings in addition to the outer ring spacer or the inner ring spacer, the bending stress acting on the inner and outer rings of the bearing is greatly reduced, and the bearing ring is damaged. It is possible to prevent defects such as cracks. As a result, the load load limit value as a multi-row combination ball bearing can be increased.

  In addition, when adjacent ball bearings in parallel combination are arranged without the outer ring spacer and the inner ring spacer, each line connecting the radial center points of the contact ellipse in the outer ring raceway groove from the ball center of one ball bearing. At least one of the extension lines does not intersect with the axial end plane of the other ball bearing, and at least one of the extension lines of each line connecting the radial center of the contact ellipse in the inner ring raceway groove from the ball center of the other ball bearing. One may be configured not to intersect the axial end plane of one ball bearing. Thereby, the contact angle is set to be large so that the axial load is increased, and both rolling fatigue life and prevention of damage can be achieved.

It is sectional drawing of the multi-row combination ball bearing which concerns on 1st Embodiment of this invention. It is sectional drawing which expands and shows the ball bearing of the parallel combination of FIG. It is sectional drawing which shows the modification of the multi-row combination ball bearing of this invention. It is a front view of a general electric injection molding machine. It is a principal part enlarged view of a general electric injection molding machine. It is sectional drawing of the conventional multi-row combination ball bearing.

  Hereinafter, a multi-row combination ball bearing according to each embodiment of the present invention will be described in detail with reference to the drawings. In addition, the multi-row combination ball bearing according to each embodiment includes the ball screw support bearing for clamping, the ball screw support bearing for ejector shaft, the ball screw support bearing for injection, and the ball screw for nozzle touch described in FIGS. Although it is assembled as a support bearing, only a multi-row combination ball bearing is illustrated and described here.

(First embodiment)
As shown in FIG. 1, in the multi-row combination ball bearing 10 of the present embodiment, three rows of angular ball bearings 11A, 11B, and 11C are arranged in combination, of which two rows of angular ball bearings 11A and 11B are arranged. Arranged in parallel, and two rows of angular ball bearings 11B and 11C are arranged in rear combination.

  Each of the angular ball bearings 11A, 11B, and 11C includes an outer ring 12 having an outer ring raceway groove 12a on an inner peripheral surface, an inner ring 13 having an inner ring raceway groove 13a on an outer peripheral surface, and an outer ring raceway groove 12a and an inner ring raceway groove 13a. And a ball 14 that is arranged to freely roll with a contact angle α, and a cage (not shown) that holds the ball 14. As each of the angular ball bearings 11A, 11B, and 11C, an inner and outer diameter dimension and a width dimension corresponding to an ISO standard bearing are used.

  The groove shoulder 12b on one side (right side in the figure) of the outer ring 12 is axially extended so that the outer ring raceway groove 12a on the side through which the extension line L of the contact angle α passes is longer than the center of the ball 14. It is formed higher than the groove shoulder 12c on the other side (left side in the figure). Further, a counter bore 12d that is inclined so as to increase in diameter toward the other side in the axial direction is formed on the groove shoulder 12c of the outer ring 12 opposite to the side through which the extended line L of the contact angle α passes with respect to the center of the ball 14. Is formed on the inner peripheral surface. The counter bore 12d has a shape necessary for inserting a ball during assembly of the bearing. Further, from FIG. 2, the inclination angle β of the counterbore 12d is preferably 3 degrees or more and 15 degrees or less. When the inclination angle β is smaller than 3 degrees, the opening of the end surface of the outer ring becomes narrow, and it becomes difficult to insert the balls 14 during assembly. Further, by setting the inclination angle β to 15 degrees or less, the plane width of the axial end portion plane on the counter bore side can be secured. The mouth position 12d1 of the counterbore 12d (the boundary position between the counterbore 12d and the outer ring raceway groove 12a) is given by determining the contact angle α from the viewpoint of ball insertion during assembly.

  On the other hand, in the groove shoulders 13b and 13c of the inner ring 13, the groove shoulder 13b on one side in the axial direction is formed low so that a cage (not shown) having an inclined cross section is inserted between the inner and outer rings 12 and 13. Further, the groove shoulder 13c on the other axial side of the inner ring 13 is a groove on one axial side so that the inner ring raceway groove 13a on the side through which the extension line L of the contact angle α passes with respect to the center of the ball 14 becomes longer. It is formed higher than the shoulder 13b.

  Further, the contact angle α of each of the ball bearings 11A, 11B, and 11C is set to 60 degrees or more, and the ball bearings 11A and 11B of the adjacent parallel combination are connected to the outer ring spacer and the inner ring spacer similarly to the ball bearing 200 of FIG. When arranged without using a ball, at least one of the extended lines La and Lb connecting the radial end points a and b of the contact ellipse C in the outer ring raceway groove 12a from the ball center O of one ball bearing 11A is the other. Of each line that does not intersect with the axial end plane 12e of the outer ring 12 of the outer ring 12 of the ball bearing 11B and that connects the end points a and b of the contact ellipse C in the inner ring raceway groove 13a from the ball center O of the other ball bearing 11B. At least one of the extension lines La and Lb is configured not to intersect the axial end plane 13e of the inner ring 13 of the one ball bearing 11A. That is, when the outer rings 12 and the inner rings 13 of the ball bearings 11A and 11B are arranged in contact with each other, the line connecting the radial center point b of the contact ellipse C in the outer ring raceway groove 12a from the ball center O of the ball bearing 11A. The extension line Lb of the ball bearing 11B passes the inner diameter side of the axial end portion plane 12e of the outer ring 12 of the ball bearing 11B, and the radial end point a of the contact ellipse C in the inner ring raceway groove 13a from the ball center O of the ball bearing 11B. An extension line La of the connecting line passes through the outer diameter side of the axial end plane 13e of the inner ring 13 of the ball bearing 11A. Thereby, in each ball bearing 11A, 11B, and 11C, the contact angle (alpha) is set large so that the load load of an axial direction may become large.

  An outer ring spacer 22 and an inner ring spacer 23 are disposed between the outer rings 12 and the inner rings 13 of the two rows of angular ball bearings 11A and 11B in parallel combination. The extension lines La and Lb of the lines connecting the ball center O of the left ball bearing 11A and the radial end points a and b of the contact ellipse C in the outer ring raceway groove 12a are the axial end planes of the outer ring spacer 22. Pass 22a. Further, the extension lines La and Lb of the respective lines connecting the radial end points a and b of the contact ellipse C in the inner ring raceway groove 13a from the ball center O of the right ball bearing 11B are the axial end portion planes of the inner ring spacer 23. Pass through 23a. In the present embodiment, the inner diameter dimension of the outer ring spacer 22 and the outer diameter dimension of the inner ring spacer 23 are set so as to satisfy these requirements.

  For example, as shown in FIG. 2, the inner diameter d is 50 mm, the outer diameter D is 110 mm, the width B is 27 mm, the contact angle α is 60 °, the ball diameter Da is 20.638 mm, and the inclination angle β of the counter bore 12d is 5 °. In the case of the ball bearings 11A and 11B, when the ball bearings 11A and 11B are arranged so that the axially opposite end planes are in contact with each other, the ball center O of the left ball bearing 11A is within the outer ring raceway groove 12a. At least one of the extended lines La and Lb connecting the radial end points a and b of the contact ellipse C does not intersect the axial end plane 12e of the outer ring 12 of the right ball bearing 11B, and the right ball bearing 11B. At least one of the extended lines La and Lb of each line connecting the radial end points a and b of the contact ellipse C from the ball center O to the inner ring raceway groove 13a is a plane in the axial direction of the inner ring 13 of the left ball bearing 11A. Interchange with 13e Not. However, as in the present embodiment, by providing the outer ring spacer 22 and the inner ring spacer 23 having a width of 5 mm, both radial ends of the contact ellipse C in the outer ring raceway groove 12a from the ball center O of the left ball bearing 11A. The extension lines La and Lb of the lines connecting the points a and b pass through the axial end plane 22a of the outer ring spacer 22 and the contact ellipse C in the inner ring raceway groove 13a from the ball center O of the right ball bearing 11B. Extension lines La and Lb of the lines connecting the radial end points a and b pass through the axial end plane 23 a of the inner ring spacer 23.

  By satisfying the above requirements as described above, when a very large thrust load is applied to the multi-row combination ball bearing 10, it occurs between the contact portions between the balls 14 and the raceway grooves 12 a and 13 a of the inner and outer rings 12 and 13. The load in the contact angle direction can be backed up by the outer ring spacer 22 and the inner ring spacer 23 without being loaded only by the inner and outer rings 12 and 13 of the ball bearings 11A and 11B. As a result, in addition to the outer ring spacer 22 or the inner ring spacer 23, the load also greatly reduces the bending stress acting on the inner and outer rings of the ball bearings 11A and 11B in the adjacent bearings 11B and 11A. It is possible to prevent problems such as damage and cracking of the ring. As a result, the load load limit value as a multi-row combination ball bearing can be increased.

  As the widths of the outer ring spacer 22 and the inner ring spacer 23 are increased, each line connecting the radial end points a and b of the contact ellipse C in the outer ring raceway groove 12a or the inner ring raceway groove 13a from the ball center O is obtained. The extension lines La and Lb do not pass through the axial end planes of the adjacent bearings 11B and 11A, but intersect the inner peripheral surface of the housing or the outer peripheral surface of the shaft. It is possible to back up with these members. Increasing the width of the outer ring spacer 22 and the inner ring spacer 23 is not particularly problematic in that a load is applied.

  In this embodiment, the counter bore is provided on the outer ring side. However, a counter bore may be provided on the inner ring side. In this case, the same effect can be obtained by appropriately setting the inclination angle of the counter bore of the inner ring 13. Is obtained.

In addition, this invention is not limited to embodiment mentioned above, A deformation | transformation, improvement, etc. are possible suitably.
For example, the multi-row combination ball bearing 10 of the present invention can be applied to a multi-row combination of 4 to 5 ball bearings 11A to 11E as shown in FIG. 3 so that a large load in one direction can be applied. Can do.
That is, the four rows of ball bearings 11B, 11A, 11D, and 11E are arranged in parallel through the outer ring spacer 22 and the inner ring spacer 23, respectively, for example, from the ball center O of the ball bearing 11A that is located in the middle in the axial direction. The extension lines La and Lb of the lines connecting the radial end points a and b of the contact ellipse C in the outer ring raceway groove 12a pass through the axial end plane 22a of the adjacent outer ring spacer 22 on one side in the axial direction. Further, the extended lines La and Lb of each line connecting the radial end points a and b of the contact ellipse C in the inner ring raceway groove 13a from the ball center O of the ball bearing 11A are adjacent to the inner ring spacer 23 adjacent on the other side in the axial direction. Passes through the axial end plane 23a.

10 multi-row combination ball bearings 11A, 11B ball bearing 12 outer ring 12b, 12c groove shoulder 12d counter bore 13 inner ring 13b, 13c groove shoulder 14 ball 22 outer ring spacer 22a axial end plane 23 inner ring spacer 23a axial end plane α Contact angle C Contact ellipse L Extension line La, Lb Extension line O connecting the ball center to the radial end point of the contact ellipse O Ball center

Claims (3)

In a multi-row combination ball bearing comprising at least two rows of ball bearings in parallel combination, and a counter bore formed on at least one groove shoulder of the outer ring and inner ring of each ball bearing,
The ball bearings correspond to ISO standard bearings whose inner and outer diameters and widths are
Between the adjacent ball bearings of the parallel combination, an outer ring spacer and an inner ring spacer are arranged,
Of the adjacent ball bearings of the parallel combination, the extension line of each line connecting the radial end points of the contact ellipse in the outer ring raceway groove from the ball center of one of the ball bearings is the axial end plane of the outer ring spacer And an extension line of each line connecting the radial center ends of the contact ellipse in the inner ring raceway groove from the ball center of the other ball bearing passes through the axial end plane of the inner ring spacer. Multi-row combination ball bearing.   When the adjacent ball bearings of the parallel combination are arranged without the outer ring and the inner ring spacer, the extended lines of the respective lines connecting the radial center points of the contact ellipse in the outer ring raceway groove from the ball center of the one ball bearing. At least one of the extension lines of each line that does not intersect with the axial end plane of the other ball bearing and connects the end points in the radial direction of the contact ellipse in the inner ring raceway groove from the ball center of the other ball bearing. The multi-row combination ball bearing according to claim 1, wherein one of the ball bearings does not intersect an axial end plane of the one ball bearing. At least three rows of the ball bearings are arranged in a parallel combination via the outer ring spacer and the inner ring spacer, respectively.
Among the ball bearings of the parallel combination, an extension line of each line connecting the radial center ends of the contact ellipse in the outer ring raceway groove from the ball center of the ball bearing located in the middle in the axial direction is adjacent on the one side in the axial direction. An extension line of each line passing through the axial end plane of the outer ring spacer and connecting the radial center of the contact ellipse in the inner ring raceway groove from the ball center of the ball bearing located in the middle of the axial direction is the other side in the axial direction. The multi-row combination ball bearing according to claim 1 or 2, wherein the multi-row combination ball bearing according to claim 1 or 2 passes through an axial end plane of the adjacent inner ring spacer.

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