JPH0361071B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention comprises a piston member having a spring portion housed in a cylindrical cylinder, the piston member being caused to protrude by supplying pressure fluid, and the piston member being equipped with a return function. This invention relates to a spring piston device operated by the action of a tabular spring section.

(Prior art) In chucks for clamping workpieces in machine tools, or in pile chucks or clamps in pile driving machines, pressure fluid such as hydraulic pressure or pneumatic pressure is supplied to drive a piston in order to clamp and grip an object. It has an extrusion machine. Some devices use a spring piston such as a spring chuck to return the piston that has been pushed out in this way.

As an example, as shown in FIG. 5, a piston 2 is slidably housed in a cylindrical cylinder 1.
By introducing pressure fluid from the supply port 4 into the rear chamber 3a defined by the piston 2 inside the cylinder, the piston 2 moves to the left in the figure and pushes the ram 5 out of the cylinder 1. The return of the piston 2 and ram 5 is performed by a spring 6 built into the front chamber 3b of the cylinder 1.

This spring piston configuration has the advantage that a pressure fluid supply control system such as hydraulic pressure can be omitted in order to obtain the return power of the piston 2.

(Problems to be Solved by the Invention) In the spring piston device having the above configuration, the cylinder 1
cannot be made smaller because it needs to be large enough to accommodate the structure in which the spring 6 is wound around the outside of the ram 5. Also, since the piston and ram float without being fixed to the cylinder, steps are required to prevent them from falling off. It is necessary to provide a stopper such as part 7, which has the disadvantage of complicating the structure.

SUMMARY OF THE INVENTION An object of the present invention is to simplify the piston drive control system by using a configuration in which a piston reciprocating within a cylinder is biased in one direction by the action of pressure fluid and returned in the opposite direction by the force of a spring. It is an object of the present invention to provide a spring piston device that can be miniaturized without impairing efficiency or function, and can be suitably used for all kinds of clamps or chucks.

(Means for Solving the Problems) The present invention provides a piston member having a hollow cylindrical shape with an open rear end and a spring portion in the middle portion, with an open tip and a pressure fluid supply port at the rear end. The piston member is housed inside a cylindrical cylinder member, and the rear end of the piston member is fixed to the innermost part of the cylinder member.

(Operation) When pressure fluid is introduced into the piston member from the pressure fluid supply port of the cylinder member, the piston member receives a force that pushes it out from inside the cylinder. However, since the rear end of the piston member is fixed at the innermost part of the cylinder member, the spring section provided in the middle of the piston member expands and absorbs the pressure of the fluid introduced into the inside of the cylinder member. . That is, at this time, only the front end portion of the piston member protrudes from the cylinder member. By protruding the piston member in this manner, it is possible to obtain a clamping action for various chucks or clamps.

When the supply of pressure fluid to the inside of the cylinder member is stopped, the spring portion of the piston member draws the front end portion of the piston member into the inside of the cylinder member by its elastic force. At this time, the fluid within the cylinder member flows out.
This causes the piston member to return and provide a release condition in the chuck or clamp.

(Embodiment) Fig. 1 is a partially cutaway perspective view showing an embodiment of the present invention, Fig. 2 is a side sectional view illustrating an operating state, and Fig. 3 is a side view of a piston member.

In the figure, reference numeral 11 denotes a cylindrical cylinder member having an opening at its front end. This cylinder member 11 is blinded by a rear wall 11a having a supply port 12 for pressure fluid. The piston member 13 housed inside the cylinder member 11 has a hollow shape with only the rear end open, and has a spring portion 14 in the middle portion in the length direction.

The spring portion 14 in this embodiment is formed by forming a slit 15 which passes through from the outer surface to the inner surface in a spiral shape in the circumferential direction. That is, the front end 13a and rear end 13 of the piston member 13 are separated by the spiral slit 15.
b are connected by a coiled spring portion 14. As a result, under normal conditions, the front end 13a and rear end 13b of the piston member are in a state close to each other, but when the rear end 13b is fixed and the front end 13a is pulled forward, the spring portion 14 expands. Thus, the front end 13a and the rear end 13b can be separated. Further, when the tension on the front end portion 13a is released, the elastic force of the spring portion 14 causes the front end portion 13a to contract and return to its original state.

The piston member 13 is fitted into the cylinder member 11 from the rear end 13b, and is attached to a fastening member 1 such as a screw while in contact with the rear wall 11a of the cylinder member 11.
It is fixed at 6.

Reference numeral 17 denotes a packing that seals the contact surfaces of the cylinder member 11 and the piston member 13 near their front ends in an airtight or watertight state. Numerals 18 and 18 are gaskets for sealing the fixing member 14 and the cylinder member 11 together. These packskins 17, 18, 1
8 hermetically seals the interior space of the piston member 13 except for the supply port 12.

The operation of the piston device having the above structure will be explained with reference to FIG.

In FIG. 2, the upper half of the piston member 13 is in its normal initial state. That is, the spring portion 14 in the central portion of the piston member 13 maintains the length l1 in the normal state and is in the shortest state to the piston member 13.
Therefore, fluid such as compressed air or pressure oil is supplied to the cylinder member 1 through the pipe P connected to the supply port 12.
When the spring portion 14 is introduced into the piston member 13, the pressure of the fluid causes the spring portion 14 to expand to a length l2. As a result, as shown in the lower half of FIG. 2, the front end 13a of the piston member 13 protrudes forward and comes into contact with, for example, a fixed pawl A forming a chuck or clamp. Therefore, if an object to be clamped, such as a workpiece or a stake, is interposed between the front end portion 13a and the fixing claw A, it is possible to effectively clamp and fix the workpiece.

When the supply of pressure fluid from the supply port 12 is stopped, the pressure applied to the piston member 13 is released, and the front end portion 13a of the piston member is pulled back into the cylinder member 11 by the action of the spring portion 14. Of course, at this time, the fluid inside the piston member 13 to the cylinder member 11 flows backward through the supply port 12 and is discharged. In this way, the piston member 13 automatically returns to its original position without actively applying a restoring force.

Although the above embodiment employs a chuck structure with a fixed pawl and a movable pawl, the piston devices of the present invention may be arranged oppositely to enlarge the effective clamping range. Furthermore, the present invention can be applied not only to clamping devices such as chucks and clamps, but also to reciprocating mechanisms in general equipment.

In this way, in this embodiment, main components such as a return hydraulic pressure source and a spring can be omitted, so the device can be made smaller. Therefore, with the same installation space, it is possible to make the piston larger, increasing its strength against buckling and lateral loads, and
Compared to a conventional cylinder with the same thrust, the inner diameter can be made smaller, and with the same inner diameter, the fluid pressure used can be lowered, making it possible to reduce the cost of parts used and the failure rate.

In the above embodiment, one spiral slit 15 is provided in the piston member 13 to constitute the spring portion 14, but the spring portion may be constituted by two or more spiral slits as required. In addition, the spring portion 14 is not provided with a spiral slit, but with a slit 1 formed from opposite sides of the piston member 13 as shown in FIG.
The expandable and contractible spring portion 14 can be constructed by alternately cutting the holes 9 and 19 into the shape of notches. in this way,
It can be seen from FIGS. 3 and 4 that there are various methods for providing the slits for constructing the spring portion 14. Further, although a cylindrical piston member is used in the above embodiment, the piston member is not limited to this, and may of course be a prismatic cylinder having a rectangular cross section or the like.

A case will be described in which the spring piston device 34 of this embodiment is used in a pile driver.

First, with reference to FIG. 6-1, a case will be described in which the pile driver 30 is placed on an existing pile 33 and used for clamping when press-fitting or pulling out a pile or self-propelling on the pile. In this case, the overall length is shorter than that of the conventional cylinder mechanism 32 shown in FIG. 6-2, and L4<L3, so the clamp 31 can be downsized and can be used in a narrow space.

FIG. 7-1 shows an example in which the spring piston device 34 is used in a chuck 36 for press-fitting and pulling out the pile driver 30. With the omnidirectional rotating chuck that is normally used, it is possible to attach it to the back side of the sheet pile 33 without changing the size of the chuck 36, so it is possible to take up space inside the chuck 36. It is now possible to install equipment such as an auger in the middle 35, increasing work efficiency. Of course, it goes without saying that the above-described spring piston device itself also has its own effects.

(Effects of the Invention) As explained above, according to the present invention, a piston member having a spring portion formed in the intermediate portion is housed in a cylinder member, and the spring portion is expanded by introducing pressure fluid into the inside of the piston member. By protruding only the front end of the piston member and stopping the supply of pressure fluid, the spring part can self-return, so the configuration is simple as only two main elements, the cylindrical cylinder member and the piston member, are required. Compared to the conventional configuration that requires a separate spring, it is possible to reduce the size and weight without impairing efficiency and function, and the shape of the cylinder member can also be simplified. Furthermore, a drive control system for returning the piston member to its original position can be omitted, and moreover, it can be easily and compactly applied to all types of clamps and chucks.

[Brief explanation of drawings]

Fig. 1 is a partially cutaway perspective view of one embodiment of the spring piston device of the present invention, Fig. 2 is a side sectional view illustrating the operating state, Fig. 3 is a side view of the piston member, and Fig. 4 is another embodiment. A side view of the piston member in the example, FIG. 5 is a partially sectional side view of a conventional spring piston device, and FIG. 6-1 is an explanatory side view showing the state in which the spring piston device of the present invention is attached to the clamp of a pile driver. , FIG. 6-2 is an explanatory side view showing a conventional example of a clamp for a pile driver, and FIG. 7-1 is an explanatory plan view showing a state in which the spring piston device of the present invention is attached to the chuck of a pile driver. FIG. 7-2 is an explanatory plan view showing a conventional example of the chuck of a pile driver. DESCRIPTION OF SYMBOLS 11... Cylinder member, 12... Pressure fluid supply port, 13... Piston member, 14... Spring part.

Claims (1)

[Claims] 1. A piston member having a hollow cylindrical shape with an open rear end and a spring portion in the middle portion is housed inside a cylindrical cylinder member with an open front end and a pressure fluid supply port at the rear end, A spring piston device characterized in that a rear end portion of the piston member is fixed to the innermost portion of the cylinder member.