JPH0741021U - Hollow piston rod connection structure - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a hollow piston rod connection structure in which the fatigue fracture strength of a welded part does not change and durability is stable. [Structure] The inner surface 10 of the end of the hollow rod 1 and the outer surface of the insertion end 20 of the rod head 2 are respectively threaded with screws. After the two are screwed together, the outer surface contact portion 4 is fixed by welding.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a hollow piston rod connection structure for a hydraulic cylinder.

[0002]

[Prior art]

 Generally, a hollow piston rod of a hydraulic cylinder is used to reduce its weight and has a structure as shown in FIG. 2. More specifically, as shown in FIG. The insertion ends 20 and 30 of the rod head 2 and / or the rod end 3 (both in this case), which have a diameter slightly larger than the diameter of the hollow portion, are press-fitted into the hollow portion of Is connected and fixed by welding.

In such a structure, when a tensile load is applied to the hollow piston rod, this load is shared by the holding force at the press-fitting portion and the fixing force at the welded portion.

[0004]

[Problems to be solved by the device]

 However, the holding force of the press-fitting part varies in proportion to the tightening allowance of the press-fitting, so if the tightening allowance is not constant, the load on the welded part also changes.

On the other hand, since the insertion portions 20 and 30 of the rod head 2 and the rod end 3 which are press-fitted into the hollow rod portion are slightly larger than the diameter of the hollow rod portion, the press-fitting tightening margin is often. However, there is a problem that the fatigue fracture strength of the weld decreases and fatigue fracture occurs in the case where the tightening margin is small in many cases. In addition, because of such drawbacks, the application of hollow piston rods has been restricted in places where the tensile load is large, and there has been a problem that the purpose of weight reduction has not been utilized.

The present invention has been made in view of the above problems of the prior art, and it does not change the fatigue fracture strength of the welded portion in any case, and the connection of the hollow piston rod is stable. It is intended to provide structure.

[0007]

[Means for Solving the Problems]

 Therefore, the connection structure of the hollow piston rod according to the present invention is such that the connection of the hollow piston rod in which the insertion end of the rod head or / and the rod end is inserted into the hollow portion of the hollow rod end portion and fixed by welding. The structure is basically characterized in that the inner surface of the end portion of the hollow rod and the outer surface of the insertion end of the rod head or / and the rod end are threaded with each other. is there.

[0008]

[Action]

 The hollow rod of the hollow piston rod, the rod head, and the rod end are each threaded with a predetermined screw and screwed together. According to the connection by screwing, when the dimension of the thread cutting is within the tolerance, the change in the holding force is small. Therefore, when a tensile load is applied to the piston rod, the load shared by the threaded portion is a constant value, and the load shared by the welded portion is also constant. Therefore, the load distribution is stable in the hollow piston rod. Will be obtained.

[0009]

【Example】

 A specific embodiment of the present invention will be described with reference to the drawings. The present invention is not limited to the following embodiments.

FIG. 1 is a partial cross-sectional view showing a main part of a hollow piston rod in which the connecting structure of the present invention is used, and here, a connecting structure between a hollow rod 1 and a rod head 2 is shown.

The hollow rod 1 is internally threaded on the inner surface 10 of its end, and the rod head 2 is externally threaded on the outer surface of its insertion end 20, which are screwed together.

That is, the two are connected by screwing the insertion end 20 of the rod head 2 into the hollow rod 1. Then, as shown in the figure, in the screwed state, the outer surface abutting portion 4 of both is fixed by CO ₂ welding.

As described above, in the present embodiment, since the hollow rod 1 and the rod head 2 are screwed together, if the dimension of the thread cutting is within the tolerance, the change of the holding force thereof will occur. Becomes smaller, and when a tensile load is applied to the entire connected piston rod, the load shared by the threaded portion becomes a constant value, and the load shared by the welded portion also becomes constant. It has a stable and durable hollow piston rod. Therefore, it can be easily used even in a place where the tensile load is large, and the original purpose of reducing the weight can be effectively exhibited.

In this embodiment, only the connecting structure between the hollow rod 1 and the rod head 2 is shown, but it goes without saying that this structure can also be applied to the rod end.

[0015]

[Effect of device]

 As described above, according to the connection structure of the present invention, a hollow piston rod can be obtained in which the fatigue fracture strength of the welded portion does not change and the durability is stable. Therefore, it can be easily used even in a place where a large tensile load is applied, and the original purpose of the hollow piston rod, which is to reduce the weight of the device, can be effectively exerted.

[Brief description of drawings]

FIG. 1 is a partial sectional view of a hollow piston rod in which the connection structure of the present invention is used.

FIG. 2 is a partial cross-sectional view showing an outline of a general hollow piston rod.

FIG. 3 is a partial sectional view showing a connection structure of the hollow piston rod in FIG.

[Explanation of symbols]

 1 Hollow rod 2 Rod head 3 Rod end 4 External contact part 10 Rod inner surface 20 Rod head insertion end 30 Rod end insertion end

Claims (1)

[Scope of utility model registration request] 1. A hollow piston rod connecting structure in which an inserting end of a rod head or / and a rod end is inserted into a hollow portion of an end portion of the hollow rod and is fixed by welding, the end portion of the hollow rod. An inner surface and an outer surface of the insertion end of the rod head or / and the rod end,
Hollow piston rod connection structure characterized by cutting screws that are screwed together.