Cycle Initiation with Light Curtains

Cycle Initiation

Cycle initiation is a concept when the machine is designed so that a new cycle starts when you take your hand out from the light curtain. A cycle is defined as the hand being placed and taken out once. Usually it is possible to choose between one-cycle and two-cycle operation. During one-cycle a new press stroke is started when the light curtain has been cleared once. The operator thereby operates the press by the action of putting parts in and out.

Because the press starts without any particular command, there are some risks involved and therefore many conditions have to be met before the machine operates.

To restrict the usage to smaller presses which cannot be entered there are the following limitations. The table height may not be lower than 750 mm, the stroking length may not be larger than 600 mm and the table depth may not be larger than 1000 mm. The light curtain shall have 30 mm or tighter resolution. If the press is not started within approximately 30 seconds after the end of the cycle, a new cycle should not be accepted without the light beam being again manually reset.

Note: For machines with cycle initiation, the installation of the light curtain must be in accordance with machine parameters and all relevant standards and regulations.

Installation of Light Curtain

The light curtain must be installed so that no one can reach a trapping/crushing risk without actuating the light curtain. The most important thing is that there are no gaps under, on the sides and over the top during cycle operation. The lower edge of the light curtain must therefore be slightly below the press table edge. Also if it is open above the light curtain, the height must be adapted so that it is not possible to reach over the protection area (see EN 294). Possible physical adjustment possibilities must be limited so that no gaps can occur.

Between the light curtains protection area and mechanical parts there shall only be maximum 75 mm gap to prevent a human from standing there. In practice to achieve this demand and the required safety distance one usually has to complement with additional mechanical protection or additional horizontally positioned light curtains (i.e. step-in light curtain). Another solution could be a lying or an angled light curtain.

Installation - Correct and Incorrect during Cycle Initiation

Correctly Installed

The operator cannot reach into the machine without actuating the Light Curtain.

Incorrect Installation

Gap below the Light Curtain. The operator can reach into the machine without actuating the light Curtain.

Correctly Installed

Light Curtain complemented with a horizontal Light Curtain to detect the operator.

Incorrect Installation

Gap above the Light Curtain. The operator can reach into the machine without actuating the Light Curtain.