How a uniquely silent cable carrier system supplies a high speed linear loader

KABELSCHLEPP AMERICA, Milwaukee--Silent, dynamic and reliable – these were the demands on a new Linear Loader to be developed by the Handling system specialist W. Strothmann GmbH. Extremely silent linear motors were chosen for the drive of this loader, the suitable cable drag chain was found in QUANTUM of KABELSCHLEPP. But why was this product chosen?

Strothmann develops and produces special machines, especially handling systems, for more than 25 years now. Companies such as Gildemeister, Mahle, INA or Miele are among the customers of the medium-sized company having 90 employees. Strothmann has agencies in the most important European countries, the USA, Mexico, Canada and China.

ROBOTRAX is suitable for swiveling and turning movements. Therefore all cable carrier tasks on a swivel arm robot can be fulfilled by one system. For the guidance of the chain, two different channel systems are available. For rotation of up to 700 degrees, there is variant A with linear run, whereas variant B in a cone arrangement is suitable for rotation of up to 360 degrees. However, the use of guide channels is not required in many application.

Picture 1: For the linear loaders of Strothmann silent linear motors are used together with the wear resistant QUANTUM cable drag chains.

For the drive of a new, silent linear loader for the Hanover Fair 2002 (picture 1) linear motors was chosen. The reasons: On the one hand they need low maintenance as there are no other wear parts than the mechanical guidance. On the other hand they can reach high travel speeds of up to 5,5 m/s and accelerations of up to 20 m/s2. As a countermove constructive problems had to be solved. For example, the magnetic fields of the horizontal and the vertical drive must not influence one another. Furthermore a stable system for the long travel lengths is necessary. A further advantage of linear drives is the vibration-free operation.

Fast, silent and highly loadable

Such demands must of course also be guaranteed by the cable drag chain. First challenge: Common cable drag chains cause vibrations due to its design as the joint links build a polygon and cause the so-called polygon effect when they are running. Therefore Strothmann required a highly loadable chain which runs vibration-free. From an earlier project they were already in contact KABELSCHLEPP, whose QUANTUM cable drag chain came up to the requested demands (picture 2).

Picture 2: Since 1951 KABELSCHLEPP develops cable drag chains for an increased service life of supply lines.

In contrast to common cable drag chains which consist of joint links of limited pitch, QUANTUM is made from an extruded plastic material with inside steel ropes. Therefore this series has no wear causing links. This specialty is responsible for the extremely smooth run and the high lifetime. The noise emission remains under 40 db(A). The high lifetime is proved during endurance tests in the test laboratory of KABELSCHLEPP: A QUANTUM system has already done more than 25 Mio. strokes, without any failure coming up.

The lack of links offers new application fields for this design: As no wear is caused by links and the cable wear is reduced by the use of Aluminium stays, QUNATUM is suitable for clean room applications as they are found for example in electronic production works and in the aviation and space travel industries.

Also the other properties of Quantum meet the demands of Strothmann: The chain allows operation speeds of 40 meter per second and accelerations of 30 m/s2. Furthermore, QUANTUM offers a high resistance against ultraviolet rays and against lubricants and coolants. Furthermore the chain can be extended later on. So the investment into Quantum will be protected if the installation should be extended at a later date. The required longitudinal connector is also hinged so the smooth run is not disturbed.

Optimum adaptation to all application conditions

QUANTUM is available in four sizes with bend radii between 60 and 600 mm. Different stay variants allow for optimum adaptation to every application.

A special characteristic of QUANTUM – its elasticity – opened up a second application field for this system at Strothmann. A station for oiling car body sheets had to be developed for an automobile manufacturer. For maintenance work this station must be moved once a day into another position, in fact, into two different directions, displaced by 15 degrees. For doing so Quantum was fixed on centre in an imagined travel line of 7,5 degrees, but in fact, the station will be moved by +/-7,5 degrees to it, being possible without any problems due to the elasticity of the chain.

Tip-off for saving:

Cable drag chains in common design are built from single links. “Simple” chains always have a pin to hole connection. When during operation the chain link first turns into the radius and then out of the radius this results into a movement, which by definition causes wear. Whenever a chain operates in the so-called “unsupported area” this wear determines the lifetime. The tolerances in the hinge increase thus causing a sag of the chain. If this becomes too big, i.e. the upper chain part nearly touches the floor in its final position, the chain must be replaced. QUANTUM does not have links and therefore no link wear can occur. That is why the lifetime is much higher than in case of common link chains.

The following diagram shows the lifetime of different chain generations. It can be seen that Quantum is 2,5 to 25 times superior in comparison to similar sizes and operational conditions.

The efficiency of QUANTUM is clearly higher than the „standard“ plastic cable drag chains. This is an important argument for the increasing demands on the performance of machines, installations and robots

One moving cycle is one stroke of the carrier there and back. This corresponds to four link movements or bends. A longer lifetime of the cable drag chain is equivalent to decreased standstill times of the complete installation and the standstill and repair costs involved.

For additional information about the Silent Cable carrier System contact KabelSchlepp America, Inc. at 7100 West Marcia Rd, Milwaukee, WI 53223-3363. Tel: 414-354-1994, Fax 414-354-1900, or e-mail us at info@kabelschlepp.com and say, "I saw it in MotionShop.com" or visit our Web site at http://www.kabelschlepp.com.

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