JPH0540610U - Variable tightening rigidity bolt - Google Patents

Abstract

(57) [Abstract] [Purpose] A tightening rigidity variable type bolt that is applied to the flange fastening part of a motor or a pump and adjusts its natural frequency. By changing the natural frequency, vibrations due to resonance can be adjusted to a small level. .. [Structure] A bolt in which the length of the threaded portion of the bolt is sufficiently long, the bolt head is circular, the screw is cut, and a nut with a long screw length is screwed onto the bolt head.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a tightening rigidity variable type bolt which is applied to a flange fastening portion of a motor or a pump, a motor stand, a pump mounting portion, etc. and adjusts its natural frequency.

[0002]

[Prior Art]

 In an electric pump, the natural frequency of the motor frame system may match the pump's rotational speed component and resonate, causing excessive vibration and disabling operation. This problem is often found only after assembly at the site.Take measures such as bringing it back to the factory to modify the frame, loosening the tightening bolts to reduce the tightening force, and lowering the natural frequency of the motor or pump. I took measures to avoid resonance.

[0003]

[Problems to be solved by the device]

 It takes a lot of man-hours and costs to bring the frame back to the factory to modify the frame, and there are problems in terms of the construction period. In addition, loosening the bolt is not preferable because it may reduce the tightening force and may cause loosening during operation.

[0004]

[Means for Solving the Problems]

 The present invention solves the above-mentioned conventional problems, in which the length of the neck and the screw portion is made sufficiently long, and the bolt head is made circular to cut the screw, and the screw head has a sufficiently long screw length. It is a variable tightening rigidity bolt that screws together with a toe.

[0005]

[Action]

 The effective length of the bolt is adjusted by adjusting the screwing position between the nut having a sufficiently long screw length and the threaded bolt head. The tightening rigidity of the bolt decreases as the effective length increases. Therefore, if this type of bolt is used in a place where the bending moment that affects the frame vibration is large and the tightening rigidity of the bolt is reduced, the rigidity of the frame decreases and the natural frequency decreases. On the contrary, if the tightening rigidity is increased, the natural frequency can be increased.

[0006]

【Example】

 1 to 3 show a variable tightening rigidity type bolt according to a first embodiment of the present invention, wherein FIGS. 1 and 2 are longitudinal sectional views, FIG. 3 is a plan view, and FIGS. 4 and 5 show a second embodiment. FIG. 1 to 3, the head 2 of the bolt 1 is formed in a circular shape, and a screw 3 is cut on the outer circumference thereof. The under neck of the bolt 1 and the screw portion 4 are sufficiently long, a nut 5 having a sufficiently long screw length is screwed into the screw 3, and a nut 6 is screwed into the screw portion 4. Reference numerals 7 and 8 are flange portions. Generally, the bolt 1 is a hexagon socket head cap screw. 1 shows the case where the effective bolt length l is small, and FIG. 2 shows the case where 1 is large.

[0007]

[Effect of the device]

 4 and 5, the nut 5 is formed in a tapered shape, and the rigidity of the nut is also changed to further enhance the effect of the present invention.

[0008] As example of analysis of the present invention is applied to a real machine, the vibration value of the motor frame is greater close to the motor frame system natural frequency 22.2H _Z in pump rotational frequency 20 H _Z in the case of FIG. 6 , and half the effective length l of the fastening bolt, as shown in FIG. 7, increasing the number of motor frame natural frequency from 22.2H _Z in 23.7H _Z, resonance or these evasion increases, vibration Goes down. ΔV in FIG. 7 is a vibration reduction width.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a variable rigidity bolt according to a first embodiment of the present invention, where l is short.

FIG. 2 shows a case where l is long in FIG.

FIG. 3 is a view taken along the line AA of FIG.

FIG. 4 is a vertical cross-sectional view of a second embodiment of the present invention, where l is short.

5 is a case where 1 is long in FIG.

FIG. 6 is a case where the effective length l of the bolt is long due to the fluctuation of the frequency and the vibration value.

FIG. 7 is a case where the effective length l of the bolt is short due to the fluctuation of the frequency and the vibration value.

[Explanation of symbols]

 1 Tightening rigidity variable type bolt 2 Bolt head 3 Bolt head screw 4 Bolt screw part 5 Nut to be screwed to the bolt head 6 Nut 7, 8 Flange part l Effective bolt length

Claims (1)

[Scope of utility model registration request] 1. The length under the neck and the threaded portion are made sufficiently long, the bolt head is made circular, and a screw is cut, and a nut having a sufficiently long screw length is screwed onto the bolt head. Variable tightening rigidity type bolt.