Summary of basic information on the use and design of air cylinders

Today, we are going to discuss the "Summary of basic information on the use and design of air cylindersA note on the "What is the best way to use air cylinders?　This is a summary of notes on the use of air cylinders for beginners in design.

Precautions for using air cylinders

(1) Notes on the thrust of air cylinders

The air to drive the air cylinders needs to be adjusted and the air pressure in the factory where it will be installed needs to be known and adjusted.

Generally, air in a factory is set at 0.5 to 0.7 MPa (N/mm2), but in a large factory, the factory may add more and more lines, leak, or add air blowers on site, so if air cylinders are designed with air pressure, in case the air pressure If the air pressure drops, the thrust may not be sufficient if the thrust was designed with high pressure, etc.It should be designed so that the capacity is sufficient even at 0.3 MPa (N/mm2).

So I'd like to note thatTube I.D. (cylinder I.D.) is different for the inside area of the cylinder on the push side and on the pull side.　And that,Different air equipment manufacturers may have different thrust even at the same specification pressure.

More on this in our blog.Theoretical Thrust Table　Please check there.

(2) How to use the stroke of the air cylinder

When the air cylinder is used in a pushing motion,As a stroke guide, it is necessary to allow an excess of about 5 mm to avoid using up the entire stroke.

This is the same on the push side and the pull side,For example, if a 100-station air cylinder is used at its maximum, the internal structure will act as a stopper and force cannot be applied beyond that point.The air cylinders can be custom-made to any stroke dimension.　Although air cylinders can be custom-ordered and manufactured with any stroke dimension, standard stroke products are basically purchased from the standpoint of price and delivery time.

And when trying to see the operation of the air cylinder with the attached sensor,Assume that a very small amount of strokes will still be detected by the sensor.Therefore, if you are using a very small amount of strokes, it would be better to consider the sensor.

Air cylinders such as chucks may not respond well to sensors if the amount of movement before and after operation is too small.

(3) Shock absorption of air cylinder

There are four main types of air cylinder shock absorption.

1. Provide a fixed mechanical stopper externally.
2. Provide a fixed mechanical stopper + shock absorber externally.
3. Use the air cylinder optional stopper.
4. Relieve with internal parts of air cylinder. (rubber cushion and air cushion)*1

1 In many cases, the shock-absorbing mechanism of the cylinder itself does not function because the entire air cylinder stroke is not used in most cases when the cylinder is used for pushing motion.

What we should be concerned about here is the life span and failure of the shock absorber.　Most of them are used with external stoppers (some of them are integrated), but if you use them, you need to consider their life span carefully.Not as long-lasting and environmentally sensitive as I expected.It can be.

In this blogCalculations for the RB series, often used as shock absorbers　And,Examples of NG use of shock absorber　Please also note the following information if necessary.

4) Risks and countermeasures against lateral loading

The longer the stroke of an air cylinder, the more attention must be paid to "lateral load.　As is the case when the stroke is short, when the stroke of an air cylinder is long, it is necessary to check in the catalog of the air cylinder used whether the lateral load is within the allowable value when the piston rod is subjected to a lateral load. Lateral load can cause the piston rod to bend, air leakage due to long-term use, and buckling of the piston rod.

If a horizontal load is applied and an air cylinder that does not have a guiding function such as a "guided air cylinder" is used, a "guiding mechanism" must be provided.　While referring to the values in the manufacturer's catalog, please design the product with the environment in which it will be used in mind. A guide is always necessary.

As for this.Design method to prevent air cylinder failure　Please refer to the detailed notes in the following section.

(5) Single-acting cylinders and two-stage stroke cylinders

This is my personal idea, but I hear that single-acting cylinders often fail to operate (I personally have no such experience), so I would like to avoid using them as much as possible, and I will also design the two-stage stroke type to avoid using them as much as possible.　The two-stage stroke is easier to understand and quicker to deliver if two air cylinders are used if necessary.

(6) Catching during operation

Interferes with thrust.Sliding part snagging　It is necessary to pay attention to the following.　It is not the inside of the cylinder, but the parts on the sliding surfaces that catch each other.

When the air cylinder is moving, the pressure decreases, but when it stops sliding due to trapping, the pressure increases, and when the trapping is released, the cylinder makes a shocking motion.

I think it is set by regulator etc., so I don't think the pressure will be higher than that.Dangerous if not carefulIt is. While dangerous to people, it is also harmful to equipment, so be very careful of "sliding parts.

(7) When using an air cylinder to raise and lower the machine, be careful how the air is used in the ascent and descent.

It is especially difficult to adjust the speed on the descending side or to add "low pressure", so it should be considered difficult to control by air when descending is considered.　As for ascendingCautions when using air cylinders in lifting operations　Please refer to the detailed explanation in the following section.

(8) If protective covers and sensors are not used, use a system in which the drive switch is pressed with both hands.

Without experience in the field, it is surprisingly difficult to understand where the dangers are.　When a cylinder is driven by a switch at the operator's discretion, it is dangerous to press the switch with one hand.　It is necessary to use both hands or install an area sensor to prevent the cylinder from being driven even if a person enters the work area.

(ix) When a heavy object for a press is suspended from an air cylinder, be careful not to drop it.

Air cylinders are often used as lifting actuators, but it is important to note the possibility of failure of the power source factory air.

Measures must be taken to prevent damage to personnel or equipment in the event of a power source failure.　Specifically, a power failure may cause a drop in pressure, resulting in a decrease in thrust, causing the workpiece to come off the machine or fall off if a load is applied to it. Such accidents can occur when the return side is controlled by air, so as countermeasures, an external stopper should be installed or the workpiece can fall off the machine.Cylinder with lock functionIf you want to shut off the airperfect blockYou can use such as (Some installers installed pull springs to prevent falling)

(10) Consider that synchronization of air cylinders is not possible.

Air cylinders are subject to individual errors, etc,Synchronized pushing operation using two or more cylinders will not work well because the same speed setting will not be maintained in each environment.

Other (Supplemental)

This section summarizes the basic items that should be considered for maintenance and preservation of equipment that uses air cylinders.

• Piping from air in the plant shall be provided with an air combination (with a minimum filter) per groove.
  *This should be taken into consideration especially when using solenoid valves.

• Air piping should be designed so that "large pipe diameter → small pipe diameter → air cylinder".
  *If the piping becomes "small pipe diameter -> large -> small -> air cylinder" and so on, problems such as pressure loss will occur.

• Air cylinders to be used should be of the same manufacturer.

• It is better for the site to concentrate the instruments, so the mounting position should be concentrated as much as possible.

• As for the site, color coding and labeling on air hoses and piping would be nice to consider.
  *It will be possible to immediately restore the system by replacing the broken one, etc.

Finally.

The times,Shift from "air" to "robot　However, I believe that the era of air cylinders will continue, so let's keep good design in mind.

That's it.