JPS6044085B2 - Cylinder for chuck - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a cylinder that restricts the operation of the chuck jaws of a chuck that grips the workpiece when processing the workpiece in a machine tool, and the cylinder is used for processing the workpiece. It relates to something that rotates at high speed together with the chuck.

[Conventional technology]

A plurality of chuck claws provided radially on the front surface of the chuck are fitted into, for example, a sloped groove of a shifter, and as the shifter moves forward and backward, the chuck claws are moved radially inside.
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A hydraulic cylinder is used to move the shifter forward and backward, and the opening and closing of the pawl is regulated by connecting the piston shaft of the cylinder and the shifter, and each cylinder chamber is divided by a cylinder piston for operating the cylinder piston. The supply of pressurized oil to the chuck is controlled by a directional control valve, and the hydraulic cylinder and chuck rotate at high speed around the piston shaft during workpiece machining.

[Problem that the invention seeks to solve]

When gripping a workpiece with the chuck jaws, a cylinder piston connected to the chuck that regulates the opening and closing of the chuck jaws is actuated, and pressurized oil is supplied to the cylinder chamber that restricts the chuck jaws in the closing direction, and the other cylinder Drain the oil from the chamber, move the cylinder piston, and pull the piston shaft in the direction of gripping the workpiece.

After gripping the workpiece, preparation for processing is completed.

However, when machining a workpiece, the chuck and hydraulic cylinder rotate at high speed, so the chuck jaws located radially to the rotation axis generate centrifugal force due to the high-speed rotation, and this centrifugal force acts in the direction of releasing the workpiece. The gripping force of the chuck jaws becomes weaker. The higher the rotation speed, the stronger the centrifugal force becomes, which poses problems such as a reduction in the gripping force of the chuck jaws and poor machining accuracy.Therefore, there is a limit to high-speed rotation, that is, a limit to the efficiency of machining work.

In addition, if the gripping force of the chuck jaws is strengthened in consideration of centrifugal force, gripping scratches may remain on the workpiece, or the chuck jaws or the chuck itself may be damaged due to the strength of the chuck jaws against the workpiece or the strength of the chuck itself. etc., and there is a limit to strengthening the gripping force of the chuck jaws, and the above-mentioned drawbacks cannot be overcome.

[Means for solving problems]

In order to solve the above-mentioned drawbacks, the present invention regulates the opening and closing of the chuck jaws by the reciprocating movement of a cylinder piston connected to the chuck, and also controls the supply of pressurized oil to each cylinder chamber for cylinder piston operation using a directional control valve or the like. In the chuck device controlled by the chucking device, the oil supply/discharge port of the cylinder chamber that obtains the work gripping thrust is provided near the piston shaft, and the oil supply/discharge port of the cylinder chamber that obtains the workpiece release thrust is provided near the inner circumference of the cylinder. This is characterized in that the increase in pressure caused by the centrifugal force of the oil generated by the rotation of the cylinder is applied to the cylinder piston, thereby increasing the chucking force.

[Effect]

Chucking of a workpiece is carried out as in a normal cylinder by supplying pressurized oil controlled by a directional valve from the oil supply/discharge hole to the cylinder chamber that generates the thrust for gripping the workpiece, and then moving the cylinder piston to the other side of the cylinder chamber that generates the thrust for releasing the workpiece. , close the chuck jaws, and grip the workpiece.

At this time, the opening of the cylinder chamber which obtains the work release thrust. The oil is discharged from the oil supply/discharge hole in the cylinder chamber according to the movement of the cylinder piston, and after the chuck jaws grip the workpiece, the filling pressure in the cylinder chamber that provides the workpiece gripping thrust is maintained. Scraping occurs due to force and force from gripping the workpiece. The position of the under piston is stabilized.

Next, the machining operation begins, and the chuck and the cylinder connected to the chuck rotate at high speed, but as mentioned above, centrifugal force is generated in the chuck jaws in the direction of releasing the grip.

On the other hand, the cylinder chamber that receives the work gripping force of the cylinder, which also rotates at high speed, is kept at a constant pressure and is in a sealed state, and centrifugal force is generated in the filled oil as the cylinder rotates.

The centrifugal force becomes larger as it moves away from the piston axis, which is the axis, and acts on the inner circumferential surface of the cylinder, but the inner circumferential surface of the cylinder does not succumb to the generated centrifugal force and rebounds, and the oil particles repel between each other. As a result, the end surface of the cylinder and the opposing surfaces of the cylinder piston are pressed together, and the cylinder piston is pressurized in the direction of the work gripping thrust.

Since the oil supply and discharge port is located near the piston shaft j, the centrifugal force generated does not dissipate from the oil supply and discharge port, and centrifugal force is also generated in the cylinder chamber that obtains the other work release thrust. There is a possibility that this may occur and act on the cylinder piston, but it may occur if the oil supply/discharge port is located far from the axis of the cylinder. Since it is installed near the inner circumference of the cylinder, the centrifugal force generated disappears from the oil supply/discharge port and does not act on the cylinder piston.

Therefore, as the cylinder rotates, the pressure in the cylinder chamber that provides the workpiece gripping thrust increases, pushing the cylinder piston in the direction of the workpiece gripping thrust, and on the other hand, the oil in the cylinder chamber that provides the workpiece release thrust is pushed out from the oil supply and discharge port of the chamber. This allows the centrifugal force of the chuck jaws to release the workpiece due to high-speed rotation to be offset, or even more pressurized to be obtained, thereby making it possible to maintain and propel the workpiece gripping thrust.

The principle by which centrifugal force is generated in the oil-filled cylinder chamber and acts on the cylinder piston is explained, for example, in the ``Compendium of Fluid Engineering.''
(written by Takesuke Fujimoto, published by Yokendo), Chapter 1 Fluid Dynamics, Four Rotating Liquids (pages 5-6) clearly states this.

〔Example〕

FIG. 1 is a partially longitudinal side view showing the embodiment, in which a plurality of chuck claws 17 are arranged radially from the center on the front surface of the chuck 16.
is provided, and the workpiece 1 is removed by opening and closing the chuck jaws 17 in the inward and outward directions.
8. Grip and release.

The opening/closing movement of the chuck claw 17 is achieved by slidingly fitting the chuck claw 17 into a slope groove of a shifter (not shown) provided with a gradient groove, for example, and opening/closing the chuck claw 17 by moving the shifter back and forth. The shifter is moved by being connected to the piston shaft 5 of the cylinder 1 located at the rear. That is, when the cylinder piston 2 moves backward and the shifter is pulled, the chuck claws 17 close and grip the workpiece, and in the opposite case, the chuck claws 17 open and release the workpiece. Therefore, the chuck side of the cylinder chamber divided by the cylinder piston 2 of the cylinder 1 becomes the cylinder chamber 3 which obtains the work gripping thrust, and the other becomes the cylinder chamber 4 which obtains the work release thrust.

An oil supply/discharge port 6 for supplying and discharging oil is opened near the piston shaft 5 of the cylinder chamber 3 that obtains the thrust for gripping the workpiece, and a communication hole 8 with an operator valve 7 installed in the middle is connected via a rotary joint to a directional control valve. via oil supply source (
(both not shown).

The operator valve 7 is actuated by the pressure difference between the cylinder chamber 3 and the communication hole 8, from which the valve seat 9 obtains the thrust for gripping the workpiece, and is operated by a spring that is biased in the opening direction when the pressure inside the cylinder chamber 3 increases during high-speed rotation. 10 and close the communicating hole 8.

The pressure difference between the cylinder chamber 3 and the communication hole 8 that generates the workpiece gripping thrust occurs when the cylinder 1 rotates and centrifugal force of oil acts on the cylinder chamber 3. By closing the communication hole 8, the pressure difference between the cylinder chamber 3 and the communication hole 8 is created. This prevents affected workpieces from falling off even if the oil supply pressure is cut off due to a power outage or failure during work.

In addition, in order to prevent the pressure caused by centrifugal force from becoming higher than necessary, a bypass passage 11 is provided in the valve seat 9, and a spring is provided that biases a ball 12 that opens and closes the bypass passage 11 to a closed state. It is best to adjust the elastic force of No. 13 (Figure 2).

On the other hand, an oil supply/discharge port 15 is provided near the inner periphery 14 of the cylinder chamber 4 from which the other work release thrust is obtained, and the port 15 communicates with an oil supply source (not shown) via the aforementioned directional valve. Then, by alternately introducing pressurized supply from the oil supply source into the cylinder chamber 3, which obtains the workpiece gripping thrust, or the cylinder chamber 4, which obtains the workpiece release thrust, using a directional control valve, the cylinder piston can be moved from side to side. It is what you do.

Note that if the cylinder chamber 4 that provides the workpiece release thrust is filled with air instead of oil, the centrifugal force generated in gas is weaker than in liquid, so that the cylinder chamber 4 that provides the workpiece gripping thrust is filled with air instead of oil.
The increased pressure caused by centrifugal force can be used more effectively.

〔Effect of the invention〕

In a conventional hydraulic cylinder, even if pressurizing action occurs on the cylinder piston due to the centrifugal force of oil, the present invention eliminates the work gripping thrust that is generated in both cylinder chambers and is eventually canceled out. In addition to creating a difference in pressure increase due to centrifugal force between the cylinder chamber that generates the workpiece gripping thrust and the cylinder chamber that generates the workpiece release thrust, the oil supply/discharge port of the cylinder chamber that generates the workpiece gripping thrust is provided near the piston shaft to create a cylinder that generates the workpiece release thrust. By providing the chamber's oil supply/discharge port near the inner periphery of the cylinder, the increase in pressure caused by centrifugal force is generated only in the cylinder chamber that generates the workpiece gripping thrust, making it possible to increase the gripping force of the chuck jaws. The rotation of the chuck cancels out the decrease in gripping force caused by the centrifugal force of the chuck jaws, and provides a constant chucking force, making work safer and more efficient.

[Brief explanation of drawings]

Fig. 1 is a partially longitudinal side view showing an embodiment of the present invention, Fig. 2 is a principle diagram showing the pressing action on the cylinder piston due to centrifugal force, and Fig. 3 is a partial view showing another embodiment. be.

Claims (1)

[Claims] 1. In a chuck device that regulates the opening and closing of chuck claws by the reciprocating movement of a cylinder piston connected to the chuck, and controls the supply of pressurized oil to each cylinder chamber for cylinder piston operation using a directional valve, etc. The oil supply/discharge port of the cylinder chamber that obtains the workpiece gripping thrust is provided near the piston shaft, and the oil supply/discharge port of the cylinder chamber that obtains the workpiece release thrust is provided near the inner circumference of the cylinder. A chuck cylinder characterized by increasing the chucking force by applying the increased pressure caused by the centrifugal force of oil to the cylinder piston.