JPH08247105A - Pneumatic cylinder - Google Patents

Abstract

PURPOSE: To provide a pneumatic cylinder in which a piston can be quickly moved even after it has been stopped for a long period of time. CONSTITUTION: Ports 8, 9 are formed to both ends of a cylinder block 1 having a piston chamber 2, and a piston 3 that is reciprocated by the compressed air being supplied through the ports 8, 9 is provided inside the piston chamber 2. A packing 4 for preventing the leakage of compressed air from the piston chamber 2 is provided to the outer circumference of the piston 3, and O-rings 10, 11 on which the outside end surfaces of the piston 3 positioned in the terminal of its stroke are abutted are provided to both the end peripheral walls of the piston chamber 2. Since the leakage of compressed air inside the piston chamber 2 can be prevented by the O-rings 10, 11, the contact pressure between the packing 4 on the outer circumference of the piston 3 and the circumferential wall of the piston chamber 2 can be reduced, and the sticking of the packing 4 to the circumferential wall of the piston chamber 2 in the case where the piston 3 has been held in a stopped condition for a long period of time can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic cylinder mainly used in a yarn supplying mechanism of a knitting machine.

[0002]

2. Description of the Related Art An example of a flat knitting machine conventionally used is shown in FIG. In the illustrated flat knitting machine, a carrier 51 having a recess 50 at the upper end and a yarn feeder 50a for guiding the knitting yarn Y at the lower end is provided movably in the horizontal direction along a guide rail 52. ing. On the other hand, the pin 5 is attached to the carriage 54 that is fed in the horizontal direction while moving the needle 53 up and down.
5 is provided so as to be able to move up and down, and when this pin 55 is lowered, it engages with the recess 50 so that the carrier 51 moves together with the carriage 54. When the pin 55 rises, the pin 55
And the recess 50 are disengaged, and the carrier 51 is released from the carriage 54.

A plurality of carriers 51 are provided in parallel, and a plurality of pins 55 are provided corresponding to each carrier 51.
Therefore, by switching the elevation of each pin 55, it is possible to switch the yarn according to the knit pattern. The pneumatic cylinder E is used to switch between the up and down movements of the pin 55.

As shown in FIG. 4, the pneumatic cylinder E has ports 62 formed at both ends of a cylinder block 61 having a piston chamber 60, and a piston 63 that reciprocates by compressed air supplied from each port 62. A rod 64 provided in the piston chamber 60 and provided at one end of the piston 63 is projected to the outside of the cylinder block 61, and a packing 65 is provided on the outer periphery of the piston 63. The packing 65 strongly presses the inner surface of the cylinder block 61 to prevent the compressed air from leaking from the piston chamber 60.

In the flat knitting machine shown in FIG. 3, the tip of the rod 64 is connected to the pin 55, and the pin 55 moves up and down as the piston 63 reciprocates. An air hose 66 that supplies compressed air is connected to each port 62.

[0006]

However, in the pneumatic cylinder as described above, when the piston 63 is stopped and a long time elapses, the packing 65 is inserted into the piston chamber 60.
When the pin 55 was switched up and down, the timing at which the piston 63 started to move was delayed, the pin 55 did not engage with the recess 50, and stitches were skipped or misaligned.

Therefore, an object of the present invention is to provide a pneumatic cylinder in which a piston moves quickly even after a long stop.

[0008]

In order to solve the above-mentioned problems, the present invention provides a piston which reciprocates by compressed air supplied from the ports by forming ports at both ends of a cylinder block having a piston chamber. In a pneumatic cylinder provided in a piston chamber and provided with packing on the outer periphery of the piston for preventing leakage of compressed air from the piston chamber, an O-ring in which the outer end surface of the piston located at the end of the stroke contacts the peripheral walls of both ends of the piston chamber. That is, the configuration with is adopted.

[0009]

According to the pneumatic cylinder of the present invention, the outer end surface of the piston located at the end of the stroke abuts the O-ring to prevent the compressed air from leaking from the piston chamber. Therefore, the packing on the outer periphery of the piston and the peripheral wall of the piston chamber are prevented. It is possible to reduce the contact pressure with and to prevent the packing from sticking to the peripheral wall of the piston chamber when the piston is held in a stopped state for a long time.

[0010]

Embodiments of the present invention will be described below with reference to the accompanying drawings. As shown in FIG. 1, in a pneumatic cylinder C according to the present invention, a piston 3 is provided in a piston chamber 2 formed inside a cylinder block 1, and a packing that is in pressure contact with the peripheral wall of the piston chamber 2 is provided on the outer periphery of the piston 3. 4 are provided. A rod 6 is provided on one end surface of the piston 3 so as to project to the outside from an opening 5 formed at one end of the cylinder block 1. The other end of the cylinder block 1 is closed by a cover 7.

At both ends of the cylinder block 1, ports 8 and 9 are formed, one end of which opens at the outer peripheral surface of the cylinder block 1 and the other end of which opens at both sides of the piston chamber 2. O-rings 10 and 11 are provided on the peripheral walls of both ends of the piston chamber 2.
Is provided.

Now, in FIG. 1, when compressed air is sent from one of the ports 8 to the piston chamber 2, the piston 3 moves upward, and accordingly, the rod 6 moves in a direction to be drawn into the cylinder block 1. . When compressed air is further sent, the right end surface of the piston 3 is an O-ring 11.
Abut and stop.

When compressed air is sent into the piston chamber 2 from the other port 9, the piston 3 moves downward, and accordingly, the rod 6 moves in a direction projecting from the cylinder block 1 to the outside. When compressed air is further fed, the left end surface of the piston 3 comes into contact with the O-ring 10 and stops.

As described above, in the pneumatic cylinder C, the outer end surface of the piston 3 is pressed against the O-ring 10 or 11 by the compressed air when the piston 3 is stopped at the end of the stroke. Therefore, even if the contact pressure between the packing 4 and the peripheral wall of the piston chamber 2 is made lower than the contact pressure between the packing 65 and the peripheral wall of the piston chamber 60 of the conventional example shown in FIG. 4, the compressed air in the piston chamber 2 leaks. Never.

By lowering the contact pressure between the packing 4 and the peripheral wall of the piston chamber 2, it is possible to prevent the packing 4 from sticking to the peripheral wall of the piston chamber 2 when the piston 3 is held in a stopped state for a long time. .

The same piston 3 and packing 4 as the conventional one are used, and the inner diameter of the piston chamber 2 is φ10 mm of the conventional one.
On the other hand, when φ10.3 mm is set, Table 1 shows the magnitude of the maximum static friction force acting on the piston 3.

[0017]

[Table 1]

When the pneumatic cylinder C is used in a flat knitting machine instead of the pneumatic cylinder E shown in FIG. 3, the rod 6 is used.
Is connected to a pin 55, and an air hose 66 is connected to each of the ports 8 and 9.

Further, as in the pneumatic cylinder D shown in FIG. 2, one end of the port 9 may be opened at the end surface of the cylinder block 1. When this pneumatic cylinder D is used in a flat knitting machine, an air hose 66 is connected to the port 8 and a spring 12 for pressing the pin 55 downward is provided between the cylinder block 1 and the pin 55.

The air hose 66 may be connected only to the port 8 of the pneumatic cylinder C, and a spring for pressing the pin 55 downward may be provided between the cylinder block 1 and the pin 55. The air hose 66 is connected only to the port 9. And pin 55
The cylinder block 1 and pin 5
It may be provided between the five.

[0021]

As described above, according to the present invention, since the outer end surface of the piston located at the end of the stroke contacts the O-ring, the compressed air in the piston chamber is prevented from leaking.

Therefore, by lowering the contact pressure between the packing on the outer periphery of the piston and the peripheral wall of the piston chamber, the packing is prevented from sticking to the peripheral wall of the piston chamber when the piston is held in a stopped state for a long time, and the piston starts to move. It is possible to prevent the timing from being delayed.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of a pneumatic cylinder according to the present invention.

FIG. 2 is a view showing a mounting state of a flat knitting machine according to another embodiment.

FIG. 3 is a view showing a state in which a conventional pneumatic cylinder is mounted on a flat knitting machine.

FIG. 4 is a sectional view of a conventional pneumatic cylinder.

[Explanation of symbols]

 1 Cylinder block 2 Piston chamber 3 Piston 4 Packing 8, 9 Port 10, 11 O-ring

Claims (1)

[Claims] 1. A cylinder block having a piston chamber is provided with ports at both ends thereof, and a piston that reciprocates by compressed air supplied from the port is provided in the piston chamber, and compressed air from the piston chamber is provided on the outer periphery of the piston. In a pneumatic cylinder provided with packing for preventing leakage, an O-ring is provided on the peripheral wall of both ends of the piston chamber, with which the outer end surface of the piston located at the end of the stroke abuts.