JP4135678B2 - Screw tightening method - Google Patents

Description

  The present invention relates to a method for screwing a first part and a second part in a press-fit state.

  For example, as shown in FIG. 2, there is a product that is completed by screwing and fixing the first component 10 and the second component 20 to each other while ensuring airtightness. In this case, the airtightness between the two parts 10 and 20 is generally ensured by arranging a seal such as an O-ring 12 between the two parts 10 and 20 (for example, Patent Documents). 1).

JP-A-5-23928

  In order to fix such two parts 10 and 20 with screws, a screw tightening device 1 shown in FIG. 7 is employed. In this apparatus 1, the first component 10 is fixed to the component holding unit 13, while the second component 20 is held by the chuck 6 connected to the vertical movable unit 3 and moves in the vertical direction. Possible and rotatable. Using this device 1, first, by pressing the component 20 toward the stationary first component 10, the second component 20 is pressed into the first component 10, and then the first component 10 is pressed against the first component 10. Thus, a method of engaging and screwing the threaded portions 11 and 21 of the components 10 and 20 by relatively rotating while pressing the second component 20 is employed.

  Incidentally, a load that presses the first component 10 and the second component 20 toward each other is generated by a spring 30 between the chuck 6 and the movable portion 3. Therefore, the magnitude of the pressing load at the time of meshing the screw parts 11 and 21 of the first part 10 and the second part 20 and at the time of screw fastening remains the magnitude required at the first press-fitting. Therefore, when the pressing load required at the time of press-fitting becomes large, it remains large when the screw portions 11 and 21 of the parts 10 and 20 are engaged with each other, and as a result, the screw portions 11 and 21 are inclined. Even if the two parts 10 and 20 are relatively rotated, there is a problem that the parts 10 and 20 cannot be securely screwed.

  Therefore, an object of the present invention is to provide a method for securely screwing the first part and the second part in a press-fit state.

  According to the screw tightening method according to claim 1 of the present invention, in the method of screw tightening the first component having the screw portion and the second component having the screw portion engaged with the screw portion in the press-fit state, Pressing the part and the second part toward each other with a first load to press-fit the first part and the second part to a certain relative distance, and the first part and the second part with the first load Engaging the screw part of the first part and the screw part of the second part by relatively rotating the first part and the second part while pressing toward each other with a smaller second load; and The first part and the second part are further rotated relative to each other while pressing the first part and the second part toward each other with a third load smaller than the second load. Screwing the two parts together. Accordingly, the first part and the second part can be relatively rotated with a pressing load smaller than the pressing load during the press-fitting stage in the meshing stage and the screw tightening stage of the screw portion, so that the first One part and the second part can be screwed together.

  Further, according to the screw tightening method according to claim 2, the magnitude of the second load is about one half of the magnitude of the first load, and the magnitude of the third load is It is about one third of the magnitude of one load.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. First, the first component 10 and the second component 20 to be screwed in the present invention will be described with reference to FIG. In the present embodiment, the first component 10 has a solid rod shape, and a male screw portion 11 is provided on the outer peripheral surface on the distal end side, and an O-ring 12 is provided on the base end side of the male screw portion 11. It is stored in the annular groove. On the other hand, the 2nd component 20 is comprised in the present Example by the upper solid part and the lower cylindrical part. Furthermore, the internal thread part 21 is provided in the inner peripheral surface of the base side at the lower cylindrical part. With such a configuration, when the second component 20 is press-fitted into the first component 10, the O-ring 12 of the first component 10 is first crushed by the inner peripheral surface of the second component 20, and then the first The male screw portion 11 of the component 10 and the female screw portion 21 of the second component 20 are engaged with each other.

  FIG. 1 is an overall view showing a screw tightening device used in the screw tightening method of the present invention. The first component 10 is held by a first component holder 13 fixed to the floor. Further, the screw tightening device 1 is fixed to the floor so as to hold the base portion 2 which is the main body of the device 1 and the second component 20 so that the second component 20 can be detachably moved up and down and rotated. It is generally composed of a vertically movable part 3 connected to the base part 2.

  In this embodiment, the vertically movable portion 3 is in the form of a slide table mounted on a vertical ball screw (not shown) fixed to the base portion 2, and the vertically movable portion 3 is interposed via the ball screw. It is connected to the vertical drive motor 4. With such a configuration, the vertical movable unit 3 can be moved up and down in the vertical direction by the rotation of the vertical drive motor 4. A balance cylinder 8 is connected between the base portion 2 and the vertically movable portion 3 to balance the weight of the movable portion 3.

  The rotating portion 5 has a gear shape in this embodiment, and is connected to the vertically movable portion 3 via a bearing on the outer peripheral surface of the hub portion of the gear. Therefore, the rotating part 5 is rotatably held by the vertically movable part 3. Since the gear teeth 51 are engaged with the teeth 71 connected to the shaft of the rotation drive motor 7, the rotation unit 5 can be rotated in the horizontal plane by the rotation of the rotation drive motor 7. Thus, the rotating part 5 is movable and rotatable in the vertical direction.

  Further, a chuck portion 6 including a pair of gripping portions 61 and 62 is held at the tip of the rotating portion 5. The pair of gripping portions 61 and 62 of the chuck portion 6 is urged to an open position for releasing the second component 20 by a spring (not shown). The gripping portions 61 and 62 are connected to a means (not shown) for supplying compressed air such as a compressor via an air passage at the center of the rotating portion 5. Thus, when the compressor is operated, the pair of gripping portions 61 and 62 of the chuck portion 6 are moved to the closed position for gripping the second component 20, and when the compressor is stopped, the gripping portions 61 and 62 are moved to the second component. Move to open position to release 20. With the above configuration, the second part 20 can be detachably moved in the up-down direction and rotatably held by the chuck portion 6.

  A sensor 9 that detects the position of the chuck portion 6, that is, the position of the second component 20, is disposed on the base portion 2. Accordingly, the second component 20 is pressed toward the first component 10 based on the position of the chuck portion 6 detected by the sensor 9, that is, depending on the press-fitting stage, the meshing stage, the screw tightening stage, and the like. In order to change the load, the force generated by the lowering of the vertically movable portion 3 is controlled by the vertically driving motor 4.

  Next, the screw fastening method of the present invention will be described with reference to FIGS. First, in the press-fitting stage, the second part 20 held by the chuck 6 is lowered toward the first part 10, and the O-ring 12 of the first part 10 does not touch the second part 20, as shown in FIG. Through the position and the position shown in FIG. 4 where the O-ring 12 of the first part 10 is crushed and is in contact with the inner peripheral surface of the second part 20, the male screw portion 11 of the first part 10 and the second part The second component 20 is lowered to the position shown in FIG. At this time, the magnitude of the first load with which the movable part 3 presses the second part 20 is selected to be a magnitude necessary for the O-ring 12 of the first part 10 to be crushed.

  Next, in the meshing stage of the threaded portion, from the position where the male threaded portion 11 of the first component 10 and the female threaded portion 21 of the second component 20 shown in FIG. The second part 20 held by the chuck 6 is moved to a position where the inlets of the female screw parts 21 of the two parts 20 coincide, that is, a position where the male screw part 11 of the first part 10 and the female screw part 21 of the second part 20 mesh with each other. Rotate relative to the first part 10. At this time, the magnitude of the second load with which the movable part 3 presses the second component 20 is not required to be large enough to crush the O-ring 12, and is smaller than the first load. Is selected.

  Finally, in the screw tightening stage, the male screw portion 11 of the first component 10 and the female screw portion 21 of the second component 20 are engaged from the position where the male screw portion 11 of the first component 10 and the female screw portion 21 of the second component 20 are engaged with each other. The second part 20 held by the chuck 6 is rotated relative to the first part 10 to the position shown in FIG. In addition, since the magnitude | size of the 3rd load in which the movable part 3 presses the 2nd component 20 at this time is converted into the force in which the force of the rotation direction by screw fastening brings the 1st component 10 and the 2nd component 20 close, It may be smaller than the second load. In this way, the first part 10 and the second part 20 can be relatively rotated with a pressing load smaller than the pressing load during the press-fitting stage in the meshing stage and the screw tightening stage of the screw portion. In addition, the first component 10 and the second component 20 can be screwed in a press-fitted state.

  The pressing load at the above stage is such that the magnitude of the second load is about one half of the magnitude of the first load, and the magnitude of the third load is the magnitude of the first load. It is preferable that it is about one third.

  Further, the forms of the stationary first component 10 and the second component 20 held by the chuck 6 may be reversed.

It is a general view which shows the screw fastening apparatus used with the screw fastening method of this invention. It is a fragmentary sectional view of the 1st component used with the screw fastening method of the present invention, and the 2nd component. It is a figure showing the state where the O-ring of the first part does not touch the second part. It is a figure which shows the state which O-ring of 1st components is crushed and is contact | abutting to the internal peripheral surface of 2nd components. It is a figure which shows the state which the external thread part of a 1st component and the internal thread part of a 2nd part contact | abut. It is a figure which shows the state which the external thread part of the 1st part and the internal thread part of the 2nd part engaged. It is a general view which shows the conventional screw fastening apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... 1st part 11 ... Thread part 20 of 1st part ... 2nd part 21 ... Thread part of 2nd part

Claims (2)

In a method of screw tightening a first part having a threaded part and a second part having a threaded part engaged with the threaded part in a press-fit state,
Pressing the first part and the second part to a certain relative distance by pressing the first part and the second part toward each other with a first load;
By relatively rotating the first part and the second part while pressing the first part and the second part toward each other with a second load smaller than the first load, Meshing the threaded part of the first part and the threaded part of the second part;
By further rotating the first part and the second part while pressing the first part and the second part toward each other with a third load smaller than the second load, A screw tightening method comprising: screwing the first part and the second part.   The magnitude of the second load is about one half of the magnitude of the first load, and the magnitude of the third load is about 3 minutes of the magnitude of the first load. The screw tightening method according to claim 1, wherein the method is one.

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