JP2007170425A - Grease supply structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a grease supply structure for uselessly and accurately supplying grease to a ball circulating in a ball nut without the need for drilling a hole in a ball screw shaft with a high degree of difficulty. <P>SOLUTION: The grease supply structure is provided for supplying the grease to a drive means which has the cylindrical ball screw shaft 10a supported on the inner peripheral face of the ball nut 10b for converting the rotating motion of the ball nut 10b into linear motion, and the ball for circulating in the ball nut 10b. It comprises a cylindrical sleeve 16 which has the ball nut 10b on the side of an inner peripheral face 16b for rotating integrally with the ball nut 10b. The sleeve 16 has a grease supply hole 19b passing through the side of the inner peripheral face 16b of the sleeve 16. The ball nut 10b has a grease supply hole 19c communicated with the grease supply hole 19b and passing through the side of an inner peripheral face 10b2 of the ball nut 10b. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a greasing structure for supplying grease to a ball nut.

  The ball screw mechanism is a mechanism that reduces the friction with the ball screw shaft by the rotation of the ball disposed inside the ball nut and efficiently converts the rotation operation into a linear operation. Therefore, in order to maximize the function of the ball screw, it is necessary to form an oil film with lubricating oil between the ball and the ball rolling surface. To that end, it is necessary to supply grease directly into the ball nut. It becomes important.

  FIG. 3 shows an example of a conventional grease supply device of a ball screw mechanism (Patent Document 1).

  An annular flange portion 81 as a rotating portion is formed at the rear end of the ball nut 51. A plurality of locations in the circumferential direction of the flange portion 81 are formed with greasing holes 82 as lubricant stabilizing paths extending in the radial direction.

  On the radially outer side of the flange portion 81, a greasing plate 83 as a greasing member made of an annular body is disposed slidably with respect to the flange portion 81. The plate 83 is fixed to the first flange 54 by bolts b <b> 2 arranged at a plurality of locations in the circumferential direction of the plate 83. Therefore, when the ball nut 51 rotates, the outer peripheral surface of the flange portion 81 and the inner peripheral surface of the plate 83 slide.

  Further, an annular oil groove 84 as a groove portion is formed along the outer peripheral surface of the flange portion 81 on the inner peripheral surface as the sliding portion of the plate 83, and at the upper end position in the circumferential direction of the oil groove 84, A greasing hole 85 as a lubricant supply path is formed in the radial direction. The radially inner end of the greasing hole 82 is opened toward an annular gap 97 formed between the ball nut 51 and the ball screw shaft 63, and the radially outer end of the greasing hole 82. The part is opened toward the oil groove 84. The greasing hole 85 has a radially inner end communicating with the oil groove 84, and a radially outer end connected to an external greasing passage.

  The nut cover 87 is disposed so as to surround the ball nut 51 and a gap formed between the flange portion 81 and the plate 83. A grease reservoir 91 is formed between the ball nut 51 and the nut cover 87. In the grease reservoir 91, grease leaked from the clearance between the outer peripheral surface of the flange portion 81 and the inner peripheral surface of the plate 83 is accumulated. Further, the grease leaked from the oil groove 84 toward the rear (left side in the figure) through a gap formed between the outer peripheral surface of the flange portion 81 and the inner peripheral surface of the plate 83 is a thrust bearing. Lubricate 58.

In addition to the above greasing device, inside the shaft of the ball screw, there is a flow path for a lubricant such as grease, one end opening at a threaded portion between the ball screw shaft and the ball nut, and the other end opening outward. An apparatus provided with a greasing path is disclosed (Patent Documents 2 and 3). According to these greasing methods, even if the ball nut rotates in the ball screw mechanism that converts the rotation operation from the drive source to the linear operation, the flow path of the grease as the lubricant is fixed, so the ball screw shaft Can be easily lubricated.
Japanese Patent No. 3522629 Japanese Patent No. 3439127 JP 2003-83416 A

  In the case of the greasing device disclosed in Patent Document 1, the flange portion 81 as the rotating portion formed on the ball nut 51 and the plate 83 that is slidably disposed on the outer periphery of the flange portion 81 are formed. A lubricant such as grease passes through the greasing holes 82 and 85 and is fed to the ball screw shaft 63. In the case of this method, the ball nut 51 is greased only when the grease that has lubricated the ball screw shaft 63 enters the ball nut 51 through the ball screw shaft 63. Therefore, reliable lubrication to the inside of the ball nut 51 is not always guaranteed.

  In addition, a grease reservoir 91 is formed in the greasing device disclosed in Patent Document 1. That is, the grease supply device disclosed in Patent Document 1 has a structure in which leakage of necessary grease supplied to the ball screw shaft 63 and the ball nut 51 is unavoidable, and therefore the grease reservoir 91 is necessary. If grease is not reliably supplied, not only may there be a problem that the ball screw does not operate properly due to increased noise or damage to the ball, but it is also necessary to continue supplying unnecessary grease. Increase in consumption and cost.

  In addition, the greasing device disclosed in Patent Document 1 is located rearward (to the left with respect to the drawing) through a gap formed between the outer peripheral surface of the flange portion 81 and the inner peripheral surface of the plate 83 from the oil groove 84. The grease that has leaked toward () lubricates the thrust bearing 58. For this reason, the lubricant for the ball screw shaft 63 and the ball nut 51 and the lubricant for the thrust bearing 58 must be the same, and the range of selection of the lubricant is limited.

  On the other hand, in order to employ the greasing method disclosed in Patent Documents 2 and 3, it is necessary to drill holes in the ball screw shaft. The hole diameter in this processing is small, and the screw length increases as the size of the machine increases, so that the processing becomes highly difficult. Therefore, there is a problem that processing time is required, resulting in high cost. Also, since the ball nut reciprocates along the ball screw shaft during machine operation, grease must always be supplied when the ball nut is in a certain position on the ball screw shaft in order to reliably supply grease inside the ball nut. In view of the length of the transmission flow path from the grease supply tank, it is extremely difficult to set the timing of grease supply by a controller that controls the operation of the machine.

  Accordingly, the present invention provides a greasing structure that can reliably grease grease to a ball circulating inside a ball nut without requiring a highly difficult process such as drilling a hole in a ball screw shaft. With the goal.

  In order to achieve the above object, the grease supply structure of the present invention is supported on the inner peripheral surface of the ball nut and circulates in the ball nut, and a cylindrical ball screw shaft that converts the rotational motion of the ball nut into a linear motion. In a greasing structure for lubricating a driving means having a ball, a ball nut is provided on the inner peripheral surface side, and a cylindrical sleeve that rotates integrally with the ball nut is provided. The sleeve includes an inner peripheral surface of the sleeve. A grease hole that penetrates to the side is formed, and the ball nut is connected to the grease hole of the sleeve, and a grease hole that penetrates to the inner peripheral surface side of the ball nut is formed. .

  As described above, the greasing structure of the present invention includes a sleeve having a greasing hole formed therein, and a ball nut in communication with the greasing hole of the sleeve and having a greasing hole penetrating to the inner peripheral surface side. . That is, the grease supply structure of the present invention can supply grease directly into the ball nut from the sleeve arranged on the outer peripheral side of the ball nut. Therefore, there is no need to prepare a holed ball screw shaft for supplying grease to the ball nut, and it is not necessary to supply the ball nut via the ball screw shaft.

  Further, in the greasing structure of the present invention, the greasing hole formed in the ball nut is located at a position corresponding to an oil groove formed in an annular shape on the inner circumferential surface of the sleeve, one end side being the outer circumferential surface side of the ball nut. It may be open.

  The greasing structure of the present invention has a cylindrical bearing case and a cover provided at one end of the bearing case, and the cover is a through hole whose one end opens at a position corresponding to the oil groove. A greasing hole may be formed. In particular, the sleeve is formed with an annular oil groove formed on the front end surface facing the cover, and an oil groove formed annularly on the inner peripheral surface, and the greasing hole includes an oil groove and an oil groove. It may be a through hole that communicates with each other. Since the oil groove is formed in an annular shape on the front end surface of the sleeve, the greasing hole of the cover always faces the oil groove formed on the front end surface of the sleeve even when the sleeve rotates. Therefore, the cover side is fixed and does not rotate in synchronization with the sleeve, but the grease supplied from the greasing hole formed in the cover is reliably supplied to the oil groove.

  Further, the grease supply structure of the present invention is such that the grease supplied from the grease hole is formed on the inner peripheral side and the outer peripheral side of the oil groove formed in an annular shape from the gap formed between the cover and the sleeve to the outside. It may have a seal member for preventing leakage. As a result, the cost can be reduced by saving the amount of grease, and the control of the amount of lubrication can be facilitated.

  The seal member may be disposed between the oil groove and a bearing housed in a bearing case that rotatably supports the sleeve. In this case, it is possible to prevent the grease that lubricates the inside of the ball nut from being mixed with the grease used for the bearing.

  As described above, according to the present invention, the grease can be directly supplied into the ball nut from the sleeve arranged on the outer peripheral side of the ball nut. For this reason, it is not necessary to drill a small diameter and long hole inside the ball screw shaft, and the cost can be reduced. Further, since the ball nut is not lubricated through the ball screw shaft, the grease can be reliably fed into the ball nut without waste.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a front view of a mold clamping device to which the grease supplying method of the present invention is applied, and FIG. 2 is an enlarged view of a portion A in FIG.

  The stationary platen 2 is fixed to the machine base 1. The movable plate 3 is fixed as an integral structure with the end plate 4 by a tie bar 6 and reciprocates together with the end plate 4. The tie bar 6 is fastened to the movable plate 3 by a tie bar nut 7. A mold 5 is installed between the fixed platen 2 and the movable plate 3.

  The stationary platen 2, the end plate 4 and the cross head 8 are connected by a link mechanism (double toggle mechanism) 9. The link mechanism 9 includes a toggle link 9a and a link pin 9b.

  The ball screw 10 is a screw mechanism that converts the rotating operation of the ball nut 10b into the reciprocating operation of the ball screw shaft 10a. The ball screw shaft 10a is fastened to the cross head 8 by a nut 11, and a linear motion converted from the rotational motion of the ball nut 10b is transmitted from the ball screw shaft 10a to the cross head 8.

  The end plate 4 is provided with a bearing mechanism 12 that rotatably supports the screw mechanism 10. Details inside the bearing mechanism 12 (part A) are shown in FIG.

  The bearing mechanism 12 rotatably holds the screw mechanism 10 with a bearing case 14, a cover 15, and a cylindrical sleeve 16. Hereinafter, the details of the bearing mechanism 12 will be described.

  First, an outline of the configuration of the bearing mechanism 12 will be described.

  The bearing case 14 is fixed to the end plate 4 by bolts 21b. A cover 15 is fixed to the cross head 8 side of the bearing case 14 by bolts 21a. Two bearings 17 are incorporated in the bearing case 14, and the sleeve 16 is rotatably supported by these bearings 17. A ball nut 10 b is accommodated in the sleeve 16. A ball nut flange 10c is provided on the rear end surface of the ball nut 10b (the lower end surface of the ball nut 10b in FIG. 2). The ball nut flange 10c, the sleeve 16, and the pulley 13 provided on the rear end face side of the ball nut flange 10c are integrated by being connected by a bolt 21c. That is, the pulley 13, the sleeve 16, and the ball nut 10b are integrated. A timing belt is wound around the pulley 13, and the sleeve 16 and the ball nut 10 b rotate when the pulley 13 is rotationally driven by a driving force of a servo motor (not shown).

  Next, the greasing structure of the bearing mechanism 12 will be described.

  An annular oil groove 20 b is formed on the inner peripheral surface 16 b of the sleeve 16. An annular oil groove 20a is also formed on the front end surface 16a of the sleeve 16 (the end surface on the cover 15 side in FIG. 2). Further, the sleeve 16 is formed with a grease supply hole 19b as a grease flow path so as to communicate the oil groove 20a and the oil groove 20b.

  Further, the ball nut 10b is provided with a plurality of grease supply holes 19c that similarly serve as grease passages so as to penetrate from the outer peripheral surface 10b1 to the internal ball circulation path. The greasing hole 19c is provided substantially at the center of the ball nut 10b, the position of the greasing hole 19c, the oil groove 20b provided in the inner peripheral surface 16b of the sleeve 16, and the greasing connected to the oil groove 20b. The positions of the holes 19b coincide.

  The rotation of the ball nut 10b and the sleeve 16 is supported by the bearing 17 as described above, but the lubricating oil sealed in the bearing 17 does not leak to the outside (downward in the figure). A seal member 18 c is disposed on the outer periphery of the sleeve 16.

  A minute gap is formed between the cover 15 that fixes and holds the bearing 17 and the front end surface 16a of the sleeve 16 in which the oil groove 20a is formed. The cover 15 is provided with a greasing hole 19a serving as a grease passage. The greasing hole 19a is provided so as to coincide with the positions of the oil groove 20a provided in the front end surface 16a of the sleeve 16 and the greasing hole 19b connected to the oil groove 20a. Further, a connecting part (not shown) such as a grease tube and a grease nipple for supplying grease to the greasing hole 19a is provided at the end of the greasing hole 19a opposite to the sleeve 16.

  Further, seal members 18 a and 18 b are disposed on the surface of the cover 15 on the sleeve 16 side and the outer peripheral surface of the sleeve 16, respectively. The seal member 18a is provided on the inner peripheral side of the oil groove 20a. The seal member 18 b is provided on the outer peripheral side of the oil groove 20 a and between the oil groove 20 a and the bearing 17. These sealing members 18a and 18b are for preventing leakage of grease supplied from the grease supply hole 19a. In other words, the seal member 18a prevents leakage from the minute gap between the cover 15 and the end surface of the sleeve 16 provided with the oil groove 20a to the ball screw shaft 10a side, thereby reducing the cost by saving the amount of grease. Reduction and easy control of the amount of greasing can be achieved. On the other hand, the seal member 18 b prevents leakage toward the outer bearing 17, thereby having the effect of not being confused with lubricating oil such as grease used for the bearing 17.

  In the bearing mechanism 12 having the above configuration, grease is supplied to the balls 10d circulating inside the ball nut 10b as follows.

  The grease is first supplied from a supply source (not shown) such as a grease pump to a greasing hole 19a formed through the cover 15 via a grease tube and a grease nipple.

  The grease supplied to the greasing hole 19 a passes through the greasing hole 19 a and flows into the oil groove 20 a on the front end surface 16 a of the sleeve 16 through a minute gap between the cover 15 and the front end surface 16 a of the sleeve 16. Since the cover 15 is fixed to the bearing case 14, it does not rotate, but the sleeve 16 rotates. However, since the oil groove 20a is formed in an annular shape on the front end surface 16a of the sleeve 16, the greasing hole 19a of the cover 15 always faces the oil groove 20a even when the sleeve 16 rotates. Therefore, the cover 15 side is fixed and does not rotate in synchronization with the sleeve 16, but the grease supplied from the greasing hole 19a is reliably supplied to the oil groove 20a.

  The grease flowing into the oil groove 20a passes through the greasing hole 19b and flows into the oil groove 20b.

  The grease that has flowed into the oil groove 20b formed in an annular shape on the inner peripheral surface 16b of the sleeve 16 flows into the greasing hole 19c formed at a position corresponding to the oil groove 20b of the ball nut 10b. The greasing hole 19c is formed in the ball nut 10b so as to penetrate to the ball circulation path of the ball screw shaft 10a accommodated in the ball nut 10b, that is, to penetrate from the outer peripheral surface 10b1 side to the inner peripheral surface 10b2 side. Yes. Therefore, the grease supplied into the grease supply hole 19c is directly supplied to the balls 10d circulating inside the ball nut 10b.

  As described above, the grease supply structure of the present embodiment includes the ball nut 10b on the inner peripheral surface 16b side, and has the cylindrical sleeve 16 that rotates integrally with the ball nut 10b. A greasing hole 19b that penetrates to the inner peripheral surface 16b side of the ball nut 10b is formed, and the greasing hole 19c communicates with the greasing hole 19b and penetrates to the inner peripheral surface 10b2 side of the ball nut 10b. Is formed. For this reason, the grease is not supplied for the first time when the grease enters the ball nut through the ball screw shaft as in the prior art, but the grease can be directly supplied to the ball nut. Therefore, the grease supply structure of this embodiment can reliably supply grease to the ball nut, and the ball screw does not operate normally due to an increase in noise caused by unstable supply of grease or damage to the ball. The occurrence of the problem can be prevented in advance.

  Further, since grease can be directly supplied in this way, it is not necessary to supply more grease than necessary, and the consumption of grease can be suppressed.

  Further, in the case of this embodiment, it is not necessary to perform a highly difficult process such as forming a long hole with a small hole diameter for supplying grease in the ball screw shaft, and the cost can be suppressed.

  In addition, although embodiment regarding a vertical injection molding machine was demonstrated, the greasing method to the ball screw proposed by this invention is applicable also to the horizontal injection molding machine which has the mold clamping apparatus of the same structure.

  In the present embodiment, the greasing hole 19c is formed only in the central portion of the ball nut 10b in the axial direction of the ball screw shaft 10a. However, the present invention is not limited to this configuration. The greasing hole 19c is provided in the center portion so that the ball nut 10b can be evenly lubricated. However, a plurality of the greasing holes 19c may be provided in the axial direction of the ball screw shaft 10a. It becomes possible to lubricate the ball nut 10b even more evenly. Also, a plurality of oil grooves 20b may be provided so as to correspond to each of the plurality of grease supply holes 19c provided in the axial direction, or may be provided wide in the axial direction so that the grease is It is good also as a structure distributed from the wide oil groove 20b to the some greasing hole 19c.

It is a front view of the mold clamping device to which an example of the grease supply device of the present invention is applied. It is the A section enlarged view of FIG. It is a sectional side view of an example of the conventional grease supply apparatus of a ball screw mechanism.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Machine base 2 Fixed platen 3 Movable plate 4 End plate 5 Mold 5a Upper mold 5b Lower mold 6 Tie bar 7 Tie bar nut 8 Cross head 9 Link mechanism 9a Toggle link 9b Link pin 10 Ball screw 10a Ball screw shaft 10b Ball nut 10b1 Outer peripheral surface 10b2 Inner peripheral surface 10c Ball nut flange 11 Nut 12 Bearing mechanism 13 Pulley 14 Bearing case 15 Cover 16 Sleeve 16a Front end surface 16b Inner peripheral surface 17 Bearings 18a, 18b, 18c Seal members 19a, 19b, 19c Grease holes 20a, 20b Oil groove 21a, 21b bolt

Claims (6)

A cylindrical ball screw shaft (10a) that is supported on the inner peripheral surface of the ball nut (10b) and converts the rotational motion of the ball nut (10b) into a linear motion, and circulates in the ball nut (10b). In a greasing structure for greasing a driving means having a ball,
The ball nut (10b) is provided on the inner peripheral surface (16b) side, and has a cylindrical sleeve (16) that rotates integrally with the ball nut (10b). The sleeve (16) includes the sleeve A greasing hole (19b) penetrating to the inner peripheral surface (16b) side of (16) is formed. The ball nut (10b) communicates with the greasing hole (19b), and the ball nut ( A greasing structure characterized in that a greasing hole (19c) penetrating to the inner peripheral surface (10b2) side of 10b) is formed.   2. The greasing structure according to claim 1, wherein one end side of the greasing hole (19 c) is an outer peripheral surface side of the ball nut (10 b) and opens at a position corresponding to the oil groove (20 b).   It has a cylindrical bearing case (14) and a cover (15) provided at one end of the bearing case (14), and one end side of the cover (15) corresponds to the oil groove (20a). The greasing structure of Claim 1 or 2 in which the greasing hole (19a) which is a through hole opened to the position is formed.   The sleeve (16) has an annular oil groove (20a) formed on the front end surface (16a) facing the cover (15) and an oil groove (20b) formed annularly on the inner peripheral surface. The grease supply structure according to claim 3, wherein the grease supply hole (19b) is a through hole that allows the oil groove (20a) and the oil groove (20b) to communicate with each other.   Grease supplied from the greasing hole (19a) is formed between the cover (15) and the sleeve (16) on the inner peripheral side and the outer peripheral side of the oil groove (20a) formed in an annular shape. The grease supply structure of Claim 3 or 4 which has a sealing member (18a, 18b) for preventing leaking from the clearance gap which is outside.   The seal member (18b) is disposed between the oil groove (20a) and a bearing (17) housed in the bearing case (14) that rotatably supports the sleeve (16). The greasing structure according to claim 5.

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