JP2007146939A - Rotating device and set screw - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent excessive deformation of an attachment member upon fixing the attachment member to a rotating shaft with a set screw even when a user fails to manage fastening torque of the set screw. <P>SOLUTION: A fragile part 16 more easily twisted than a root part 15 is formed between both ends 11a and 11b of a screw part 12 of the set screw 10, and a wrench hole 13 opened to a rear end of the set screw 10 has a depth whereby a screw part 12b on a fore end 11b side than the fragile part 16 cannot be turned in the state wherein the fragile part 16 is wrenched off, and the screw part 12b on the front end side is prevented from being turned by breakage of the fragile part 16. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a rotating device that includes a rotating mechanism that rotates via a mounting member fixed to a rotating shaft, a set screw that is screwed into a screw hole of the mounting member, and a fastening / fixing that requires torque management. It is related with a set screw suitable for.

  Examples of the rotating device as described above include a bearing unit and a torque limiter. The rotating mechanism of the bearing unit includes an inner ring (corresponding to the mounting member) fixed to the outer periphery of the rotating shaft, an outer ring arranged concentrically with the center of rotation of the inner ring, and a rolling element incorporated between the raceway surfaces of the inner and outer rings. Is included. The rotation mechanism of the torque limiter includes an internal member (corresponding to the mounting member) fixed to the rotation shaft, an external member provided to rotate concentrically with the rotation center of the co-rotating member, an internal member, and an external member. And a torque transmission member incorporated between the two.

  A set screw is often used to fix the mounting member. For example, there is a bearing unit in which radial screw holes are formed at an equal distribution of approximately 120 degrees in the exposed portion of the inner ring (see Patent Document 1). In the case of the bearing unit disclosed in Patent Document 1 described above, the set screw that is screwed into the screw hole is one in which a hexagonal wrench hole is formed at the rear end of the screw and a ball that presses against the rotating shaft is embedded at the screw front end. Yes. In some cases, a round-end or flat-end set screw is used.

  The appropriate tightening torque for the set screw is defined for each product. This is because if the set screw is tightened too much, the mounting member is cracked or excessively deformed, which adversely affects the function of the rotating mechanism that rotates through the mounting member. For example, in the inner ring of the bearing unit, the raceway surface is excessively deformed to cause early breakage, and in the internal member of the torque limiter, the torque transmission surface is deformed and the torque limiting function becomes inaccurate. Therefore, normally, the tightening torque of the set screw is managed by using a wrench having a torque limit function such as a torque wrench.

JP-A-8-232950 (FIG. 1, paragraph [0007])

  However, when using a torque wrench or the like, it is necessary to perform the operation carefully, and it takes time to perform the tightening operation. The user dislikes this, and the user may quickly tighten with a normal wrench without performing torque management. At this time, there is a fear that the fixing of the mounting member is insufficient, and there is a case where a pipe is attached to the wrench and tightened as much as possible. For this reason, conventionally, annealing or the like was applied to the mounting member to suppress deformation or the like when the set screw was tightened at a specified torque or more. However, such an increase in the heat treatment process is not preferable in terms of cost. .

  Therefore, an object of the present invention is to prevent excessive deformation of the mounting member even when the user neglects to manage the tightening torque of the set screw when fixing the mounting member to the rotating shaft with the set screw. .

  The present invention that achieves the above object includes a rotating mechanism that rotates via a mounting member fixed to a rotating shaft, and a set screw that is screwed into a screw hole of the mounting member, wherein the mounting member is the set screw. In the rotating device fixed to the rotating shaft by tightening, a weakened portion that is easier to twist than the bottom of the valley is formed between both ends of the set screw, and the screw portion on the tip side of the weakened portion breaks the weakened portion. This is to prevent it from turning.

Specifically, a configuration in which a weakened portion that is more easily twisted than the bottom of the valley is formed between both ends of the setscrew, so that the setscrew can be broken from the weakened portion so that an appropriate tightening torque is not exceeded. . Note that the fragile portion is less useful than the bottom of the valley and is not useful for regulating the tightening torque. The screw portion on the tip side of the fragile portion is prevented from turning due to destruction of the fragile portion, so that the screw portion on the tip side does not exceed the appropriate tightening torque. Here, “by breaking the fragile portion” means that the fragile portion is torn off and that the fragile portion is plastically deformed so that the screw portion on the tip side cannot be rotated any further. .
Therefore, even when the user neglects the torque management, the screw portion on the tip side does not exceed the appropriate tightening torque, so that excessive deformation of the mounting member is prevented. As a result, the heat treatment for the purpose of suppressing excessive deformation of the mounting member can be omitted.

  Preferably, in the above configuration, a configuration in which the fragile portion is positioned between both ends of the screw portion formed on the outer periphery of the set screw may be adopted. According to this configuration, when the set screw is broken, it is divided into a screw portion on the tip side and a screw portion on the rear end side in the screw hole, but each of them functions as a screw even after the division, Two screws are screwed into the screw holes. In this state, the effect of a double nut can be obtained, so that even if the screw is still broken, the divided screw portions are prevented from loosening. Therefore, even when the set screw is broken at the fragile portion, the fixing of the mounting member can be obtained, and there is no need to redo the fixing work. As a result, the user can quickly fasten the set screw without using a torque wrench or the like.

  In the above configuration, even when the wrench hole is formed farther to the tip side than the weakened portion, the screw portion on the tip side can be prevented from turning by restricting the insertion depth of the wrench. However, users cannot expect this regulation.

  Therefore, in the above configuration, it is possible to adopt a configuration in which the wrench hole opened at the rear end of the set screw has a depth that the screw portion on the tip side cannot be turned in a state where the weakened portion is threaded. With this configuration, the insertion depth of the wrench is regulated on the wrench hole side. Specifically, the wrench hole can be formed at the same depth at the rear end side or generally in the front-rear direction from the weakened portion.

  Further, if the second wrench hole communicating with the wrench hole is formed on the tip side of the fragile portion and the size of the second wrench hole is made smaller than that of the wrench hole, the wrench is used. It is possible to remove the screw part on the rear end side using the hole and to remove the screw part on the tip side using the second wrench hole. The screw can be easily replaced.

  The configuration of the set screw according to the rotating device having the above-described configuration can also be applied to a set screw used for fastening, coupling, fixing, detent, and the like of other devices and structures.

  That is, while forming a threaded portion on the outer periphery of the cylindrical portion, in the set screw in which a wrench hole opens at the rear end of the cylindrical portion, a weakened portion that is easier to twist than the bottom of the valley is formed between both ends of the cylindrical portion, It is possible to employ a configuration in which the threaded portion on the tip side of the fragile portion is prevented from turning due to destruction of the fragile portion. With this configuration, it is possible to omit heat treatment for the purpose of torque management and suppression of excessive deformation of the constituent members. Of course, a subordinate configuration such as the above-described square hole can be adopted.

  As described above, the present invention forms a fragile portion that is easier to twist than the bottom of the valley between both ends of the set screw so that the screw portion on the tip side of the fragile portion does not turn due to destruction of the fragile portion. By adopting such a configuration, when the mounting member is fixed to the rotating shaft with a set screw, even if the user neglects to manage the tightening torque of the set screw, it is possible to prevent the mounting member from being excessively deformed.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.
FIG. 1 shows the overall configuration of the rotating device according to the embodiment, and FIG. 2 shows a part of the set screw according to the embodiment when it is divided into four equal parts in the circumferential direction.
The rotating device shown in FIG. 1 is configured as a pillow-type bearing unit, and includes a rotating mechanism 1 composed of a rolling bearing having a spherical outer diameter surface and a spherical seat to which the outer diameter surface of the rotating mechanism 1 is fitted. The bearing box 2 has a vibration-proof rubber 3 on the bottom surface serving as a mounting seat for the bearing box 2.

  The rotating mechanism 1 includes an inner ring 5 (corresponding to the mounting member) fixed to the outer periphery of the rotating shaft 4, an outer ring 6 arranged concentrically with the center of rotation of the inner ring 5, and a raceway surface between the inner ring 5 and the outer ring 6. And a rolling element 7 incorporated in the housing, and a sealed type in which contact-type seals 8 are provided on both sides.

  The outer diameter surface of the outer ring 6 is the spherical outer diameter surface. The inner ring 5 is wide and protrudes to one side from the outer ring width, and a plurality of screw holes 9 are formed in the protruding portion with a required equiangular angle.

  The inner ring 5 is fixed to the rotating shaft 4 fitted to the inner diameter surface thereof by tightening a set screw 10 screwed into each screw hole 9.

  As shown in FIG. 2, the set screw 10 has a threaded portion 12 formed on the outer periphery of the cylindrical portion 11, a wrench hole 13 opened at the rear end 11 a of the cylindrical portion 11, and a ball 14 at the distal end 11 b of the cylindrical portion 11. The structure is filled with.

  The screw portion 12 is formed between the rear end 11a and the front end 11b of the cylindrical portion 11. The wrench hole 13 can be, for example, a square, hexagon, octagon, or twelve, but is not particularly limited.

  Note that the overall structure of the set screw 10 is not limited to the one described above. For example, instead of the ball 14, the tip of the set screw 10 can be formed with a round tip or a flat tip. And a wrench hole 13 can be provided with a meat part.

  Between the both ends of the threaded portion 12, a fragile portion 16 that is easier to twist than the valley bottom portion 15 is formed. In this embodiment, the rear end 11 a and the front end 11 b of the cylindrical portion 11 are both ends of the set screw 10 and both ends of the screw portion 12. Therefore, the fragile portion 16 is located between both ends of the screw portion 12.

  In this embodiment, the fragile portion 16 includes a portion in which the strength against torsion torque is lower than that of the valley bottom portion 15 by forming a thin portion in the cylindrical portion 11. The fragile portion 16 is provided by forming a groove along the spiral of the screw portion 12 over the entire outer periphery of the cylindrical portion 11. In addition, the weak part 16 may be formed so that the outer periphery of the cylindrical part 11 may extend in the circumferential direction, and can be formed continuously or intermittently on the outer periphery of the cylindrical part 11.

  The wall thickness t of the fragile portion 16 is provided so as to be surely screwed off from the fragile portion 16 in a state where the proper tightening torque is exceeded. The proper tightening torque is set so that the deformation of the inner ring 5 is within an allowable range.

  Specifically, since the appropriate tightening torque can have a certain width, the thickness t of the weakened portion 16 does not start to break at the lower limit value of the proper tightening torque, and is weak at the upper limit value. It can be set so as to be surely threaded from the portion 16. Here, the destruction occurs more accurately as the wall thickness t of the fragile portion 16 is made uniform in the circumferential direction. From this point of view, it is better that the number of corners of the wrench hole 13 is larger and the segure groove has a certain depth.

  Although the fragile portion 16 can be formed on the inner peripheral surface of the wrench hole 13, it is better to form the fragile portion 16 on the outer periphery of the cylindrical portion 11 because the configuration of the cutting process or the molding die becomes complicated.

  The wrench hole 13 is formed at the same depth in the front-rear direction from the rear end 11a side to the fragile portion 16 with respect to the fragile portion 16. For this reason, in the state where the fragile portion 16 is threaded, a wrench (not shown) addressed to the wrench hole 13 is not hooked on the screw portion 12b on the distal end side than the fragile portion 16, and the screw portion 12b on the distal end side. Is never turned. As long as this action occurs, the wrench hole 13 is allowed to be closer to the tip 11b than the fragile portion 16 is.

  In this embodiment, a second wrench hole 17 communicating with the wrench hole 13 is formed in the cylindrical portion 11. The second wrench hole 17 is a hexagonal hole coaxial with the wrench hole 13. As for the size of the second wrench hole 17, the two-surface width w <b> 2 is smaller than the two-surface width w <b> 1 of the wrench hole 13. For this reason, the wrench addressed to the wrench hole 13 does not fit into the second wrench hole 17 and the insertion depth is restricted.

  In the above configuration, the set screw 10 is screwed into each screw hole 9 in a state where the inner ring 5 is fitted to the outer periphery of the rotating shaft 4. Here, the set screw 10 is in a state of being threaded from the fragile portion 16 when a tightening torque or more is applied when tightening, and the screw portion 12b on the front end side and the screw on the rear end side in the screw hole 9 Divided into part 12a. At this time, the wrench addressed to the wrench hole 13 does not hang on the second wrench hole 17 and can no longer be turned. Therefore, the screw portion 12b on the distal end side does not rotate after dividing and does not exceed the proper tightening torque. Thereby, the fastening of the inner ring 5 and the rotating shaft 4 is restricted within an allowable range, and the inner ring 5 is prevented from being deformed excessively.

  Then, each of the threaded portion 12b on the front end side and the threaded portion 12a on the rear end side after being divided is screwed into the screw hole 9 so as to have a complete threaded portion, and functions as a screw. Play. Therefore, even when the set screw 10 is broken, the inner ring 5 can be fixed, and the user does not need to redo the fixing work.

  Further, when the set screw 10 is broken, the rear end side screw portion 12 a is extracted using the wrench hole 13, and then the front end side screw portion 12 b uses the second wrench hole 17. Extracted.

(A) is a fractured side view of the rotating device according to the embodiment, (B) is a front view thereof. Half sectional view of a set screw according to an embodiment

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rotation mechanism 2 Bearing box 4 Rotating shaft 5 Inner ring 9 Screw hole 10 Set screw 11 Cylindrical part 12 Screw part 13 Wrench hole 15 Valley bottom part 16 Fragile part 17 Second wrench hole

Claims (5)

  A rotation mechanism that rotates via a mounting member fixed to the rotating shaft, and a set screw that is screwed into a screw hole of the mounting member, and the mounting member is fixed to the rotating shaft by tightening the set screw. In the rotating device, a weakened portion that is easier to twist than the bottom of the valley is formed between both ends of the set screw, and the screw portion on the tip side of the weakened portion is prevented from turning due to the destruction of the weakened portion. Rotating device.   The rotating device according to claim 1, wherein the fragile portion is positioned between both ends of a screw portion formed on an outer periphery of the set screw.   3. The rotating device according to claim 1, wherein a wrench hole opened at a rear end of the set screw has a depth at which the threaded portion on the distal end side cannot be rotated in a state where the weakened portion is threaded.   4. The rotating device according to claim 3, wherein a second wrench hole communicating with the wrench hole is formed at a distal end side with respect to the fragile portion, and a size of the second wrench hole is made smaller than that of the wrench hole.   A threaded portion is formed on the outer periphery of the cylindrical portion, and a fragile portion that is easier to twist than the bottom of the valley is formed between both ends of the cylindrical portion in a set screw having a wrench hole opened at the rear end of the cylindrical portion. A set screw, wherein a screw portion on the tip side of the portion is prevented from turning due to destruction of the fragile portion.

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