Fluid Power

11-2001  Design Application

Inventiveness blows in better profits

Pneumatics companies are finding that the road to good profits requires being innovative and supplying complete solutions. Tom Shelley reports on developments and some special solutions

Gone are the days when fluid power vendors could expect to make a good living simply by supplying standard components.

Now, they are increasingly expected to provide solutions to meet customer needs, which means having designs which are inherently flexible, and being prepared to use ingenuity when needed.

David Snow, sales director of Camozzi Pneumatics, said recently, "It is one thing to supply straight components – everybody does that. If we can supply complete systems and solutions, on the other hand, we are able to reduce customer costs, and offer a business advantage over our competitors."

He revealed that a rapidly expanding part of his business is the supply of non-standard cylinders, sales of which were up from nearly 300 in July to more than 800 in August, and bespoke systems and inventions. The company’s newly expanded and refurbished Fluid Power Centre, in Nuneaton, produces non-standard cylinders, to order, in times which can be as short as an hour or less. It is able to do so because the cylinder bodies come as aluminium extrusions or stainless steel tubes in 3m lengths. Piston rods are similarly supplied as long lengths, so it is a simple matter of cutting bodies and rods to length and to fit them with pistons and front and rear end blocks. In the case of the cylinders with stainless steel bodies, the bodies are formed onto the end blocks to produce leak-free combinations.

In order to be able to give a more complete service, the Fluid Power Centre now offers complementary products from other members of the Italian AVS Group. These are Bonomi (UK), which supplies process valves; Avalco which supplies solenoid valves; Advanced Vacuum Services which supplies relevant pumps, regulators, switches, valves cups and holders; and CNE which supplies connectors and various sensors and proximity switches. This gives the company the capability to supply complete systems, either as kits, on mounting plates or in cabinets

It uses Pro/Engineer to speed the design work; Eureka asked if the use of CAD meant the company was able to recycle design work for different customers. David Snow said that while the CAD system was a great help in re-using designs and data when doing repeat work for the same customers, the company was very careful to separate any intellectual property used for different customers. This goes as far as refusing to supply customers who turn up with a branded part, originally made specially for a particular OEM firm, asking that Camozzi should "make one like this" for them.

Systems engineer, Barry Moyse, said that a substantial part of his team's work now involves inventing pieces of equipment to solve particular customer problems. He cited the example of the design and development of a semi-automatic tube cutter for a company which had previously used hand tools. He said most customers, however, were in the food and packaging industries as in the examples of two particularly ingenious solutions described below (or see boxes if prefer boxing them out).

Second piston makes exact backstep

A cylinder which applies the force to extrude margarine was required to step back exactly 14mm after each operation, in order to clear knives ready for the next cycle. The solution adopted was to attach two pistons to a single piston rod, and make the cylinder body in two parts.

During the operating stroke, both pistons are pushed to the end of their respective cylinders. Air pressure is then reduced in the main cylinder, and the residual pressure in the second, short cylinder, pushes the piston and piston rod back exactly 14mm. Camozzi systems engineer, Barry Moyse, explains that a two-cylinder approach is required because air is compressible, and backing off a pneumatic cylinder by exactly 14mm would require very sophisticated feedback and control. Adding the extra element to the cylinder is both lower cost and more reliable.

Margarine is used to push the main rod and piston back through the rest of the stroke, until the piston encounters a screw-adjustable stop and limit switch.

Pneumatic end stop made adjustable

The problem in this case was to design an actuator for a slide valve for a powder feeder. The requirement was to find a way of limiting the amount by which the actuator rod could retract, using a stop, which could be pneumatically actuated to move to a final position which could be manually adjusted.

The solution adopted was to have a cylinder in two parts, but with one piston attached to the main actuator rod, and the other piston attached to the end stop rod. Pressurising the end stop cylinder to a higher pressure than the actuating cylinder brings the end stop forward, and holds its position when an extension of the withdrawn actuating rod runs into it. The position which the end stop can move to is controlled by an external screw adjustment.

Robots in the valleys

Camozzi is not the only body aiming to improve its living by supplying solutions as opposed to components.

The University of Wales has a new Fieldbus Development Centre on its Allt-Yr-Yn campus in Newport. One of its permanent features is a pneumatic pick and place robot, built around Interact, Hoerbiger-Origa's fieldbus-integrated drive.

The Centre aims to demonstrate how fieldbus technology can be used to improve management and production data acquisition; improve systems maintenance through fast, intelligent diagnosis; facilitate easy modification and upgrade control systems; and reduce wiring, installation requirements and commissioning time. This is achieved through developing hands-on programmes which allow engineers and technicians to test bed fieldbus solutions and become fully conversant with fieldbus technology principles. The manager is Robert Dorr, ( E-mail address robert.dorr@newport.ac.uk ).

The robot uses both rodless and rodded cylinders and rotary actuators and grippers to provide a real world 5-axis movement. Interact intelligent actuators incorporate all ancillary control equipment, including an ASi fieldbus interface, into a standard pneumatic axis. All the electro-pneumatic controls: valves, sensors, tubing, accessories and electronics, are integrated within the Interact drive unit, so users only have to plug in an air supply. Two-way communication between the Interact drive unit and the robot's PLC controller is provided over the ASi fieldbus. The ASi bus requires only a two-wire cable for both data transmission and the auxiliary energy supply. The rotary actuator and gripper are hard wired to an ASi 'airbox' which decodes the ASi signal to actuate integral valves within the box.

The Centre is part of Allt-Yr-Yn and Caerleon Enterprises and Services (ACES) and is partly supported by the European Regional Development Fund. (More information at http://aces.newport.ac.uk/fieldbus.html )

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