JPH045762Y2 - - Google Patents

Description

[Detailed Description of the Invention] A. Field of Industrial Application The present invention relates to a device for preventing axial vibration of a sliding shaft such as a hydraulic cylinder of a fatigue testing machine due to a hydraulic load.

B. Prior Art In a fatigue testing machine using hydraulic loading, the loading hydraulic cylinder has the structure shown in ``Cylinder Actuator'' in Japanese Patent Application Laid-Open No. 60-208612, and the test piece is held between the piston rod and the crosshead and the load is applied. However, the eccentric load caused by the radial displacement of the piston rod, which is the sliding shaft, is small and is not particularly taken into account. Even in devices other than material testing machines, if radial displacement of the sliding shaft is a problem, the radial gap is made as small as possible to reduce the amount of radial displacement.

C Problems to be solved by the invention For this reason, the fatigue drive body such as a test piece connected to the sliding shaft is also displaced in the radial direction, and a material test applies a compressive load to a brittle material with high rigidity such as a ceramic material. In the case of a test piece, buckling phenomenon or eccentricity (bending) may occur in the test piece.
Stress will occur.

An object of the present invention is to provide a shaft vibration prevention device that prevents a sliding shaft from escaping in the radial direction perpendicular to the shaft center when moving in the axial direction.

D. Means for Solving the Problem At least a pair of flexible members are provided axially apart, one end of which is fixed to a sliding shaft, and the other end extending in the radial direction connected to a fixed member.

E Effect When the sliding shaft moves in the axial direction, the flexible member deforms correspondingly to the movement. At this time, the sliding shaft is restrained from being displaced in the radial direction by the fixed member via the flexible member.

F. Embodiment FIG. 1 is a sectional view in which the present invention is applied to a loading hydraulic cylinder of a fatigue testing machine. Main body frame 10
A reciprocating hydraulic cylinder 14 is installed on the underside of the table 12.
A load shaft 16 as a sliding shaft passes through the table 12 and extends upward. A gripping tool 18 is attached to the upper end of this load shaft 16, and the lower end of the test piece 20 is gripped. Therefore, due to the reciprocating movement of the hydraulic cylinder 14, a load is repeatedly applied to the test piece 20 whose upper end is held by another holding tool (not shown).

The load shaft 16 is slidably held by a bearing 22 of the hydraulic cylinder 14, and a small gap 24 between them allows the load shaft 16 to slide smoothly. A sufficiently large gap is also formed in the penetrating portion with the table 12, so that the main body frame 10 and the load shaft 16 are in a free state.

A cylindrical sleeve 26 is fitted onto the load shaft 16 and screwed with a bolt 28, and a cylindrical pipe 30 forming an annular space is arranged concentrically around the sleeve. A donut-shaped flexible member, that is, a diaphragm 32 in this embodiment, is fixed to both end surfaces of the pipe 30 and the sleeve 26 by bolts 34 and 36. This diaphragm 32 has a thick wall at the mounting surface to the sleeve 26 and the pipe 30, and a thin wall at the other central portion in order to effectively exhibit its flexibility. Also, pipe 30
is fixed by a positioning bolt 38 which is fitted into a mounting bracket 35 as a fixing member erected on the table 12, passes through a long hole 37 provided in the wall surface, and is tightened.

In the shaft vibration prevention device having such a configuration, when the hydraulic cylinder 14 is driven to repeatedly apply a load, the load shaft 16 reciprocates, and the diaphragm 32 also bends in the axial direction. At that time, the load shaft 16
is restrained in the radial direction by the mounting bracket 35 via the diaphragm 32, and is not displaced in that direction at all. As a result, no uneven load acts on the test piece 20. According to this embodiment, axial runout of the load shaft 16 is prevented, buckling can be effectively prevented especially during large deformation, and eccentric loading of highly rigid materials can be prevented, allowing accurate material testing.

In the embodiment, the pair of diaphragms 32 are arranged at one end of the hydraulic cylinder 14, but they may be arranged to sandwich the hydraulic cylinder 14, and it is sufficient to arrange the pair at least a certain distance apart. Further, the shape of the diaphragm 32 is not limited to a donut disk, but may be formed by a plurality of flexible plate pieces arranged at equal intervals in the circumferential direction. The radial lengths of the pair of flexible members do not need to be equal, but may be different, and may be arranged in three stages if necessary. Further, in the illustrated example, the elongated hole 37 may be provided on the shaft 16 side. Furthermore, it can be applied to equipment other than material testing machines in fields that require axial runout of sliding shafts.

G. Effect of the invention Since the invention is constructed as described above, it is possible to reliably prevent the shaft runout of the sliding shaft.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of the present invention applied to a material testing machine. 14...Hydraulic cylinder, 16...Load shaft (sliding shaft), 26...Sleeve, 30...Pipe, 32
...Diaphragm (flexible member), 35...Mounting bracket (fixed member).

Claims (1)

[Scope of utility model registration request] A shaft vibration prevention device comprising at least one pair of flexible members spaced apart in the axial direction, each of which has one end fixed to a sliding shaft and the other radially extending end connected to a fixed member.