JPH0339635Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention relates to a coupling mechanism between a piston of a cylinder and a piston rod.

[Conventional technology]

As shown in FIG. 4, a conventional coupling mechanism of this kind is formed at one end of a piston rod 4 from one end of a central bore 3 of a piston 2 slidably provided in a cylinder 1 of a hydraulic cylinder or the like. The narrow diameter portion 4a is hermetically fitted and protrudes toward the other end, and the nut 5 is screwed and fixed into the threaded portion 4b formed at the tip thereof.
The large diameter portion 4c and the narrow diameter portion 4a of the piston rod 4
A mechanism in which the piston 2 is tightened between the step wall 4d formed by the nut 5, or a threaded part is formed in the central inner hole 3 and the narrow diameter part 4a of the piston 2, respectively, as shown in FIG. This is a mechanism in which these are screwed and fixed, and a nut 5 is also screwed and fixed to the threaded portion 4b for connection. Note that 2a and 2b are seal members.

When pressure oil is supplied to and discharged from the pressure chambers 1a and 1b in the cylinder 1 which are divided into two by the piston 2, the piston 2 moves to the right and left together with the piston rod 4. At this time, stress due to the load acting on the cylinder 1 is acting on the small diameter portion 4a of the piston rod 4.

[Problem that the invention attempts to solve]

However, according to the prior art, a notch, which is an incompletely threaded portion, occurs at the boundary portion A between the thread bottoms of the narrow diameter portion 4a and the threaded portion 4b. As a result, the strength of the boundary portion A is significantly reduced, and there is a problem that the piston 2 may be damaged when a stress amplitude occurs due to the horizontal movement of the piston 2.

Another problem is that as the diameter of the cylinder 1 increases, the diameters of the threaded portion 4b and the nut 5 also increase in proportion to this, making it difficult to obtain sufficient tightening torque and increasing internal stress. There is a problem in that it is not possible to sufficiently increase the temperature, which may cause damage.

[Means for solving problems]

In order to solve the above-mentioned problem, the connection mechanism between the piston rod and the piston may have a different structure in which no thread is formed at the tip of the piston rod.

This idea was made in view of these circumstances, and the specific means is to pass one end of the piston rod through the central inner hole of the piston, which is slidably provided in the cylinder. In the connection mechanism between the piston and piston rod, which connects the piston and piston rod with a nut,
The piston includes a central inner hole through which the piston rod passes, and a tapered inner hole having a larger diameter at one end thereof, and a tapered inner hole having a larger diameter than the central inner hole at one end through which the piston rod passes. each having a large-diameter inner hole with a threaded portion formed on the inner periphery, and the piston rod has a tapered portion having the same inclination angle in the same direction as the tapered inner hole on the outer periphery of the portion that passes through the piston, A nut screwed into the threaded portion of the large-diameter inner hole and engaged with the outer periphery of one end of the piston rod, and a ring interposed between the tapered portion of the piston rod and the tapered inner hole of the piston. It's right there.

[Effect]

According to the above means, when the nut screwed into the threaded portion of the large-diameter inner hole of the piston is tightened, the tapered portion of the piston rod and the tapered inner hole of the piston are press-connected via the ring. This press-connected part receives the stress amplitude acting on the piston, so the tightening force at the threaded part of the nut is not affected in any way, and no thread is formed at the point where the stress amplitude acts. Therefore, stress concentration areas can be eliminated.

〔Example〕

An embodiment of this invention will be described below based on the drawings.

Incidentally, the same components as those in the prior art are given the same reference numerals and the explanation thereof will be omitted.

First, a first embodiment of this invention will be described based on FIG.

The coupling mechanism between the piston and the piston rod of this embodiment consists of a piston 2 provided in a cylinder 1 so as to be slidable in an airtight manner, a piston rod 4 having one end thereof penetrated into a central inner hole 3 of the piston 2, and the piston rod. The main components are a nut 5 which tightens and fixes the piston 4 to the piston 2, and a ring 6 interposed between the piston 2 and the piston rod 4 and between the nut 5 and the piston rod 4.

The piston 2 has a tapered inner hole 7 having a larger diameter at the end through which one end of the piston rod 4 passes through the central inner hole 3 of the piston 2, and the central inner hole 3 at the end through which the piston rod 4 penetrates. It has a large-diameter inner hole 9 having a larger diameter than that of the main body and having a threaded portion 8 formed on its inner periphery. Further, a sealing member 10 is provided inside the center inner hole 3 on the opposite side from where the tapered inner hole 7 is formed to prevent the pressure oil in the pressure chamber 1a from leaking from the vicinity of the piston rod 4.

A first tapered portion 11 having the same inclination angle in the same direction as the tapered internal hole 7 of the central internal hole 3 is formed on the outer periphery of one end of the piston rod 4 that penetrates into the central internal hole 3. 1 taper part 11
A second tapered portion 12 having the same inclination angle in the opposite direction is formed adjacent to the second tapered portion 1 .
A cylindrical rod end 13 is formed adjacent to the rod 2 .

The nut 5 has a threaded portion 14 on its outer periphery that engages with the threaded portion 8 of the large-diameter inner hole 9, and has a center hole 15 inside into which the rod end 13 is inserted. Adjacent there is a tapered fitting hole 16 having the same inclination angle in the same direction as the second tapered portion 12 of the piston rod 4.

Further, a tapered first ring 6a and a tapered second ring 6b are interposed between the first tapered part 11 and the tapered inner hole 7 of the piston rod 4, and between the second tapered part 12 and the tapered fitting hole 16, respectively. There is.

To assemble the coupling mechanism of this embodiment having the above configuration, the piston 2 is slidably inserted into the cylinder 1.
is inserted into the center inner hole 3, and one end of the piston rod 4 is passed through the center inner hole 3, and the first end is inserted into the tapered inner hole 7.
After arranging the tapered parts 11 to face each other, the first ring 6a is interposed between them, and the second ring 6b is fitted into the second tapered part 12, and then the nut 5 is inserted from one end side of the piston rod 4. Then, the rod end 13 is fitted into the center hole 15, and the threaded part 14 of the nut 5 and the threaded part 8 of the large diameter inner hole 9 are screwed together. By tightening the nut 5, the first taper part 11 and the second taper part 12 fit into the taper inner hole 7 of the piston 2 and the taper fitting of the nut 5 via the first ring 6a and the second ring 6b. Since the piston 2 is pressed into the matching hole 16, it is fixed in a predetermined position.

Next, a second embodiment of this invention will be described based on FIG.

The difference from the first embodiment is that the other outer peripheral end portion 17 of the outer periphery of the nut 5 has a threaded portion 14 formed thereon.
The piston 2 is enlarged in diameter to the same length as the outer diameter of the piston 2 and is configured to slide within the cylinder 1, so that it can also be used as the piston 2. A seal member 18 is provided on the outer periphery of this outer peripheral end portion 17 to prevent leakage of pressure oil from the pressure chamber 1b.

Further, a third embodiment of this invention will be explained based on FIG.

The difference from the first and second embodiments is that the piston rod 4 has only the first tapered portion 11, and the center hole 15 of the nut 5.
A stepped hooking portion 19 is formed inside the hooking portion 1.
By bringing the stepped portion 20 formed at one end of the piston rod 4 into contact with the piston rod 9, the first tapered portion 11 of the piston rod 4 and the tapered inner hole 7 in the central inner hole 3 are connected to the first ring 6a. It is configured so that it can be pressed through.

[Effect of idea]

According to this idea consisting of the above configuration,
Since the piston rod is not subjected to any processing that may cause notches such as screws, there is an effect that the piston rod will not be damaged. Further, since the necessary internal stress is not obtained by the tightening force of the nut, there is no need to increase the tightening torque, and therefore, it is easy to disassemble and assemble, and it can be sufficiently applied to even larger cylinders. Furthermore, since the piston is locked by the tapered surface, there is no fitting gap between the piston and the piston rod, and the concentricity between the piston rod and the piston is improved.
This has the effect of extending the life of the cylinder seal.

[Brief explanation of the drawing]

1 to 3 are sectional views of essential parts showing the first to third embodiments of this invention, and FIGS.
The figure is a sectional view of a main part showing a conventional example. 1...Cylinder, 2...Piston, 3...Central inner hole, 4...Piston rod, 5...Nut, 6
...Ring, 7...Tapered inner hole, 8...Threaded part,
9... Large diameter inner hole, 11... First tapered part (tapered part).

Claims (1)

[Claims for Utility Model Registration] A coupling mechanism in which one end of a piston rod is passed through a central inner hole of a piston slidably provided in a cylinder to connect the piston and the piston rod with a nut, the piston comprising: A tapered inner hole having a larger diameter at one end of the central inner hole through which the piston rod passes, and a threaded portion on the inner periphery and having a larger diameter than the central inner hole at one end through which the piston rod passes. the piston rod has a tapered portion having the same inclination angle in the same direction as the tapered inner hole on the outer periphery of the portion passing through the piston, and the large diameter inner hole A piston, comprising: a nut that is threaded into a threaded portion of the piston rod and that engages with an outer periphery of one end of the piston rod; and a ring that is interposed between a tapered portion of the piston rod and a tapered inner hole of the piston. and the connection mechanism between the piston rod and the piston rod.