JPH0794846B2 - Pneumatic cylinder with adjustable stop position - Google Patents

Description

TECHNICAL FIELD The present invention relates to a pneumatic cylinder whose stop position can be changed by an external operation.

[Prior Art] Pneumatic cylinders are widely used in industrial equipment.
In order to cope with the recent high-mix low-volume production, it is often necessary to reset the piston stop position of the pneumatic cylinder with a stop position accuracy of about ± 0.1 to ± 0.05 mm each time the production item is switched to match the production process. Has been done.

Therefore, there is a strong demand for the practical application of a device that can accurately and promptly and automatically adjust the stop position of the pneumatic cylinder without using human hands.

In order to change the stop position of such a cylinder, conventionally, a method of providing a mechanical stopper whose position can be changed outside or inside the pneumatic cylinder has been widely used (for example, JP-A-58-142072). See the bulletin). In such a method, by using a buffer mechanism together, ± 0.05
Although a stop position accuracy of about mm is relatively easy to obtain, it has been generally used from the past because the piston rod is made hollow and a complicated mechanism is provided on the rod side or head side cover of the cylinder tube. It is difficult to attach such a buffer mechanism. Even if a buffer mechanism can be attached, the size of the device is generally increased as a whole.

Then, without the buffer mechanism, the piston may collide with the mechanical stopper at a high speed, and after it rebounds, it may stop at a position apart from the mechanical stopper due to friction.
Therefore, in order to improve the accuracy of the stop position of the piston, the buffer mechanism is practically indispensable.

[Problems to be Solved by the Invention] An object of the present invention is to form a pneumatic cylinder having a mechanical stopper whose position can be changed at the stroke end of a cylinder tube in a relatively small size, and is generally used. The purpose is to be able to attach such a buffer mechanism.

[Means for Solving the Problems] The pneumatic cylinder of the present invention for achieving the above object is
An end block whose position can be adjusted in the sliding direction of the piston is airtightly inserted in the cylinder tube, and there is provided guide means for guiding the sliding of this end block in the sliding direction of the piston, and a screw is provided around the block. Is engraved, and a worm that is rotationally driven by appropriate means is meshed with a worm wheel that is screwed to the screw, and the end block is
Forming a flow path for compressed air to be supplied to and discharged from the pressure chamber of the cylinder,
In addition, a cushion ring on the piston rod is slidably contacted in the vicinity of the stroke end of the piston, and a hole is provided in the inner peripheral surface of the cushion packing. The present invention is characterized in that a flow passage and a bypass flow passage through a needle valve having an adjustable opening provided on the cover are provided.

[Operation] When the worm wheel is rotated by the worm, the end block screwed with the worm wheel moves in the axial direction of the piston rod, the end block moves forward or backward in the cylinder tube, and the piston stop position is set. .

After adjusting the position of the end block in this way,
When the pressurized air from the supply / discharge port to / from the pressure chamber of the cylinder is supplied / exhausted, the piston is accordingly driven within the required range set by the position of the end block. In this case, when the piston approaches the stroke end set by the end block, the cushion ring fits into the cushion packing, and the flow path from the pressure chamber to the supply / discharge port through the hole is blocked. Through the through hole and the expandable flow path, and the needle valve,
Since the air in the pressure chamber is gradually discharged, the internal pressure of the pressure chamber rises and the piston is decelerated and stopped.

[Embodiment] FIGS. 1 and 2 show a first example of a pneumatic cylinder according to the present invention.
An example is shown.

In this embodiment, the pneumatic cylinder is equipped with a piston 2 that slides in a cylinder tube 1, and a piston rod 4 that hermetically penetrates a rod-side cover 3 attached to the tube 1, and further, the tube 1 is hermetically sealed. In addition, the end block 5 is provided so that its position can be adjusted in the sliding direction of the piston.

The end block 5 is provided with a through hole 7 parallel to the piston rod 4 as a guide means for guiding the sliding of the block 5 in the piston sliding direction. A guide rod 8 for guiding sliding in the sliding direction is inserted. Therefore, the end rod 5 around the piston rod 4 is guided by the guide rod 8.
Is prevented from rotating. A screw 10 is engraved around the portion of the block 5 extending into the cover 3, and a worm wheel 11 screwed onto the screw 10 is provided in the axial direction of the piston rod 4 with respect to the cover 3. It is rotatably supported by thrust bearings 12 and 12 in a state where movement is restricted.

The worm 14, which is arranged in the tangential direction to the worm wheel 11 and meshes with the worm wheel 11, is fixed on a rotary shaft 15 that penetrates the cover 3 in an airtight manner. Is connected to the output shaft 19 of the stepping motor 18 via. Therefore, when the worm wheel 11 is rotated by driving the stepping motor 18 based on an electric signal from an electronic computer or the like, the end block 5 screwed with the worm wheel 11 moves in the axial direction of the piston rod 4 and the end block 5 is rotated. The block 5 moves forward or backward in the cylinder tube 1 to set the stop position of the piston 2.

Pressure air for driving the piston 2 is supplied to and discharged from the rod-side pressure chamber 21 in the cylinder tube 1 through the pressure-air supply and discharge port 23 provided in the cover 3, and the head-side pressure chamber 22 is supplied to the pressure chamber 22. The pressurized air is supplied and discharged through a supply and discharge port (not shown).

Thus, the cover 3 and the end block 5 are provided with a buffer mechanism for stopping the piston in a buffer manner.

The structure of the buffer mechanism itself is generally used in a pneumatic cylinder, and the end block 5 fitted in the cylinder tube 1 in an airtight manner is provided with a hole 25 which also serves as a flow path for pressurized air. The piston rod 4 is inserted into the hole 25 in a state where there is an air circulation gap, a cushion packing 26 is attached to the inner peripheral surface of the hole 25, and the piston 2 is placed at a position close to the piston 2 on the piston rod 4. A cushion ring 28, which is in sliding contact with the cushion packing 26 while being fitted into the hole 25 near the stroke end, is attached.

Further, the rod side pressure chamber 21 in the cylinder tube 1 and the supply / discharge port 23 provided in the cover 3 are made to communicate with each other by a bypass flow passage separate from the flow passage through the hole 25. In this bypass flow passage, the through hole 7 in the block 5 in which the guide rod 8 is inserted is also used as a through hole,
The pressure chamber 21 and the supply / discharge port 23 are communicated with each other through the through hole, the through hole 30 provided in the guide rod 8, and the needle valve 31 provided in the cover 3 and having an adjustable opening.

Therefore, when the piston 2 approaches the lodge-side stroke end set by the end block 5, the tip of the cushion ring 28 fits into the cushion packing 26 and the pressure chamber
The flow passage from 21 to the supply / discharge port 23 through the hole 25 is blocked, and thereafter, the air in the pressure chamber 21 gradually passes through the through hole 7 in the block 5, the through hole 30 in the guide rod 8 and the needle valve 31. Since the internal pressure of the pressure chamber 21 rises, the piston 2 is decelerated.

The second embodiment shown in FIG. 3 is different from the first embodiment in that
The structure of the expandable / contractible flow path in the bypass flow path is different. Specifically, a guide rod 38 similar to that in the first embodiment is inserted into the through hole 37 in the end block 35. ,
A through hole 39 for forming a bypass flow path is provided in the end block 35 separately from the through hole 37, and the through hole 39 and the needle valve 41 having an adjustable opening provided in the cover 33 are made of synthetic resin such as nylon. It is made to communicate with each other by a flexible pipe 42 made of.

Since the other structures of the second embodiment are the same as those of the first embodiment, the same reference numerals are given to the main parts in the drawing.

In the pneumatic cylinder of the embodiment as described above, when the positions of the end blocks 5 and 35 are adjusted, the piston is driven within the required range according to the supply and discharge of the pressure air from the supply / discharge port to the pressure chamber of the cylinder, and the buffer is provided. With the mechanism, the piston can be stopped at an accurate stop position while being driven at high speed.

Although the above embodiment shows the case where the piston stop position on the rod side of the cylinder can be changed,
The stop position on the head side or both sides can be changed.

[Effects of the Invention] As is clear from the details described above, according to the pneumatic cylinder of the present invention, when the stop position of the piston is changed, the end block is moved to the set position and the piston is driven with a necessary stroke. can do.

Further, according to the present invention, a pneumatic cylinder having a piston stop position settable by an end block and having a shock absorbing mechanism generally used is constructed as a relatively simple and small-sized one. You can

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an essential part showing a configuration of an embodiment of a pneumatic cylinder according to the present invention, FIG. 2 is a cross-sectional view of the same, and FIG. 3 is a cross-sectional view of an essential part of another embodiment. 1 ... Cylinder tube, 2 ... Piston, 3,33 ... Cover, 4 ... Piston rod, 5,35 ... End block, 10 ... Screw, 11 ... Worm wheel, 14 ... Worm, 21 ... … Pressure chamber, 25 …… hole, 26 …… Cushion packing, 28 …… Cushion ring, 30,37 …… Through hole, 31,41
...... Needle valve, 39 ...... Through hole.

Claims (1)

[Claims] 1. A pneumatic cylinder comprising a piston slidable in a cylinder tube and a piston rod which hermetically penetrates a rod side cover at one end of the cylinder tube, wherein the piston is positioned in the tube in the sliding direction. An adjustable end block is airtightly fitted and provided with a guide means for guiding the sliding of the end block in the piston sliding direction, and a screw is engraved around the block and screwed into the screw. A worm wheel rotated by appropriate means is meshed with the worm wheel, a flow path of pressure air to be supplied to and discharged from the pressure chamber of the cylinder is formed in the end block, and the cushion ring on the piston rod is near the stroke end of the piston. At the inner peripheral surface of the cushion packing that slides in the Holes and extendable flow path, as well as a bypass flow path communicating the opening adjustable needle valve provided in the cover, changeable pneumatic cylinder stop position, characterized in that in the separate end blocks.