Energy and signal supply system in gantry loaders: high speeds, quiet operation

Profile

• What was needed: P4-series profile roller chain, E4.1-series energy chains, guide troughs, and chainflex cables, all delivered as harnessed complete readychain systems.
• Requirements: The linear robots manufactured so far are 20 to 33 metres long and require correspondingly long cable guidance systems. All this has to work at speeds of 3m/s and accelerations of 7 to 10m/s².
• Industry: material handling
• Success for the customer: The P4 rol e-chains allow smooth, uniform operation over travels of up to 800m.
  The necessary chain drive power is greatly reduced and service life extended.

Energy chains are always used in the modular Gehring honing machines – in all movable axes. Here, the linear robot's Z axis with its P4 roller energy chain can be seen.

Problem

Today, the Gehring Group is among the global market leaders in precision machining. The plant manufacturer designs special horizontal machines for holes of up to 15 metres and transfer lines for producing engine blocks. The machines perform not only honing, but also other work steps such as emptying cooling lubricant residue and cleaning. All this is achieved with a high throughput – cycle times are almost always less than one minute, and high availability requirements must be met in 24/7 operation.
Since users today want the maximum flexibility, transfer lines in particular have changed. The motors are smaller, the product life cycles shorter. So we now build individual machine modules that must be connected through gantry loaders.
To offer such loaders, Gehring expanded its business area in 2014. Today, it offers a modular system for linear robots that can be used to combine different carriages, vertical axes, loading systems, and grippers.
But energy supply to these linear robots posed a major challenge: a modular machine for honing the crank case bore can be up to eight metres long. The cylinder modules require 2.60 metres, and three metres of intermediate space is needed for access. That means that the linear robots – and thus the energy chain travels – are 20 to 33 metres long. The load is also impressive: with a current project, the linear robot moves at 3m/s and an acceleration of 7m/s². However, linear robots used in a crash test station have been built for 10m/s.

Solution

For the linear robot energy supply system, the Gehring designers used our energy chains, including guide troughs and chainflex cables. Delivered as readychain systems, the e-chains are already harnessed and ready for installation. This means that Gehring gave us the necessary design data, we laid out the e-chain, manufactured, assembled, and harnessed it, and finally delivered it ready for installation, including cables.
Since the demanding combination of long travel, high travel speeds, and long service life (ten years required) cannot be achieved with a gliding chain, we specifically recommended that Gehring use the P4-series profile roller chain. Here, the rollers of upper and lower runs do not move over each other, but are offset on a wide, continuous rolling surface. This allows quiet, smooth operation, even on long travels (up to 800 m).
The autoglide crossbars ensure safe guidance, greatly reducing the drive power necessary and extending service life.
The energy supply from the linear robot, that is, from the X axis, to the loaders (Z axis), uses a chain from the E4.1 product range. Here, the undercut design ensures greater lateral stability than do conventional systems.Finally, our chainflex cables for mobile applications are also used. For the fast X axes, Gehring uses the CF27 servo cable series, which features, among other things, an additional pressure-extruded TPE inner jacket. For these cables, we guarantee ten million cycles or 36 months. CF113-series cables are used to transmit data. Their expected service life is 20 million cycles in this specific case.
The energy supply contributes to the high linear robot availability – in three-shift operation at 160 strokes per hour.

View of the Z-axis of the gantry with P4 roller energy chain.

Easily visible: the autoglide crossbars of the profile rol e-chain®.

Easily visible: the autoglide crossbars of the profile rol e-chain®.