JPH0318724Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a cylinder device that performs linear reciprocating motion using hydraulic or air pressure.

<Prior Art> When an actuated object of a machine tool or other equipment is linearly reciprocated using a cylinder device using fluid pressure, it is often necessary to prevent the piston rod from rotating. As shown in FIG. 3, a conventional piston rod rotation prevention mechanism is such that a keyway 4 is provided in the axial direction on the outer diameter of a piston rod 3 that protrudes from the front end 2 of a cylinder tube 1 and moves forward and backward. Keyway 4
The key guide system has a locking pin 5 that engages with the piston rod 3, as shown in Fig. 4.
A guide bearing 6 whose axis is parallel to the piston rod is provided, a guide bar 7 is slidably fitted into the guide bearing 6, and the guide bar 7 and the piston rod 3 are connected to the connecting rod 8.
A guide bar system is commonly used.

<Problems to be solved by the invention> According to the conventional piston rod rotation prevention mechanism using the key guide method, it is necessary to avoid interference between the keyway 4 and the gasket 2a provided on the front end 2. 3 is restricted by the length of the keyway 4. Therefore, when the length of the front end 2 in the axial direction is short, the length of the keyway 4 is also shortened, and naturally the forward and backward movement distance of the piston rod 3 is also shortened. In order to increase the distance that the piston rod 3 moves forward and backward, it is necessary to increase the length of the front end 2 in the axial direction and the keyway 4, but as the front end 2 becomes larger, the cylinder itself becomes larger. , there is also the problem of increased weight occupied by the front end 2.

Further, according to the guide bar method, a space for installing the guide bearing 6 and a space for allowing the guide bar 7 to move forward and backward is required around the cylinder.
There is a problem that it cannot be used in a narrow installation space.

The present invention provides a cylinder device using a key guide system that solves the above-mentioned conventional problems.

<Means for solving the problem> The present invention provides an axially inner hole in the axial center of the piston rod that has an opening only on the rear end surface of the piston, and fixes a guide shaft concentric with the piston rod to the rear end of the cylinder tube. the guide shaft and the inner hole are fitted so as to be able to slide relative to each other, a plurality of key grooves are provided in the inner hole and the guide shaft in the axial direction, and a key is fitted into at least one key groove, The other keyway forms a fluid pressure passage that communicates the interior of the cylinder tube behind the piston with the inner hole.

<Effect> The technical means of the present invention described above operates as follows.

The piston rod is prevented from rotating by a key fitted into a keyway of a guide shaft fixed to the rear end and a keyway of the inner hole, and the keyway of the inner hole slides along the key to move forward and backward. In addition, when the piston rod moves forward, the rear end surface of the piston excluding the cross-sectional area of the guide shaft serves as a pressure receiving surface for fluid pressure, and at the same time, fluid pressure flows into the inner hole using the other keyway in which no key is fitted as a passage. The tip surface of the inner hole also serves as a pressure-receiving surface, and the piston rod obtains the forward operating force necessary for work.

<Example> An example of the present invention will be described below based on FIGS. 1 and 2. 1 is a cylinder tube, 2 is a front end, and 14 is a rear end. A piston 9 is fitted within the cylinder tube 1 so as to be movable forward and backward by fluid pressure. A piston rod 3 is integral with the piston 9, and its tip protrudes from the front end 2 to the outside of the cylinder tube 1.

In the cylinder device of the present invention, an inner hole 10 having an opening only on the rear end surface of the piston 9 is provided in the axial center of the piston rod 3 in the axial direction.

Also, a guide shaft 1 is provided at the rear end 14 of the cylinder tube 1, which is concentric with the piston rod 3.
The base end of the guide shaft 11 is fixed, and the guide shaft 11 and the inner hole 10 are fitted so as to be relatively slidable.

Furthermore, a plurality of keyways 12a, 12b (four in the illustrated example, but two or three may be provided) are provided in the inner hole 10 and the guide shaft 11 in the axial direction,
A key 13 is fitted into a keyway 12a.

Since the present invention has the structure as described above, when fluid pressure is introduced into the rear chamber of the piston 9 in the state of the retreating end shown in FIG. Fluid pressure flows into the inner hole 10 using the key groove 12b in which the key 13 is not fitted as a passage.
The piston 9 moves forward within the cylinder tube 1 with its tip end surface serving as a pressure-receiving surface to move the piston rod 3 forward. At this time, the piston rod 3 is prevented from rotating by the key 13 and slides along the key 13.

<Effects of the invention> According to the invention, the piston rod is prevented from rotating by a key fitted in a keyway between an inner hole provided in the piston rod and a guide shaft fitted in the inner hole and fixed to the rear end. Because it uses a key guide system with a built-in piston rod, there is no need to consider the length of the front end in order to determine the forward and backward movement distance of the piston rod, making it possible to use a short front end and a position that is effective for sealing. Packing can be installed, and a large full stroke can be obtained with a small and lightweight cylinder.

In addition, although the guide shaft reduces the effective pressure-receiving area of the rear end surface of the piston, the keyway where the key is not fitted becomes a passage for fluid pressure, and the fluid pressure flows into the inner hole so that the tip surface of the inner hole becomes the pressure-receiving surface. Therefore,
The operating force required for the forward movement of the piston rod can be sufficiently obtained without any reduction in the effective pressure-receiving area.

Furthermore, if the keyway used to fit the key becomes worn out after long-term use and cannot be used as a rotation stopper, it should be replaced with the keyway used as a passage for fluid pressure. As a result, the keyway retains its anti-rotation function for a longer period of time, and the keyway, which has become unusable, can be used as a passage for fluid pressure, which has a very reasonable effect.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of the present invention, FIG. 2 is a sectional view taken along the line of FIG. 1, and FIGS. 3 and 4 are explanatory diagrams of the prior art. 1...Cylinder tube, 2...Front end, 3...Piston rod, 9...Piston, 1
0...Inner hole, 11...Guide shaft, 12a,
12b...Keyway, 13...Key, 14...Rear end.

Claims (1)

[Scope of utility model registration request] In a cylinder device consisting of a piston fitted in a cylinder tube so as to be movable forward and backward by fluid pressure, and a piston rod integrated with the piston, the piston has an opening in the axial center of the piston rod only on the rear end surface of the piston. A hole is provided in the axial direction, a guide shaft concentric with the piston rod is fixed to the rear end of the cylinder tube, the guide shaft and the inner hole are fitted so as to be able to slide relative to each other, and a plurality of keys are provided in the inner hole and the guide shaft. A cylinder device comprising grooves provided in the axial direction, a key fitted into at least one key groove, and the other key grooves forming a fluid pressure passage communicating between the inside of the cylinder tube behind the piston and the inner hole.