Power operated collet chucks KZF/KZZF - RÖHM - #7

Personnel lacking any experience in the handling of clamping devices are at particular risk of sustaining injury due to incorrect handling and usage, such injuries emanating in particular from the clamping movements and forces involved during setup work.

Clamping devices should therefore only be used, set up or repaired by personnel

specially trained or instructed for this purpose and/or who have long years of experience.

Chuck functionality should be tested after mounting prior to

commissioning.

Two important points are:

Clamping force: The clamping force specified for the clamping medium (+15%) should be achieved at max. actuation force/pressure. Stroke monitoring: Theclampingpistonstrokeshouldhavea safety range in the front and rear end position. The machine spindle should only start if the clamping piston has passed through the safety range.

Only limit sensors should be used for monitoring the clamping distance, and these should meet the requirements for safety limit sensors specified in VDE 0113/12.73 Section 7.1.3.

This module can, for technical reasons, consist in part of individual components with sharp edges and corners. Any tasksinvolvingthismoduleshouldbecarriedoutwithextreme care to prevent risks of injury!

The max. permissible speed may only be set with applied max. actuation force and clamping chucks which are functioning perfectly. Failure to observe this basic principle can lead to a loss of residual clamping force and, consequently, workpieces being thrown out of the chuck and the risk of injury associated with

this.

The clamping device should only be used at high speeds under an adequately--dimensioned safety guard.

This equipment is intended for revolving operation. Centrifugal forces created by excessive speed and/or peri pheral speed can result in individual parts loosening and becoming potential sources of danger for personnel or objects in the near vicinity. In addition to this, clamping media which are only designed for use at lower speeds but are operated at high speeds can result in unbalance which adversely affects safety and the machining results achieved. Operation at speeds higher than those permitted for these units is prohibited for the above--mentioned reasons. The max. speed and actuation force/pressure are engraved on the body and should not be exceeded. This means that the max. speed of the machine being used should not ex ceed that of the clamping device (i.e. it should be limited accordingly).

Even a singular incident where the permitted values are exceeded can lead to damage or injury and represent a hidden source of risk, even if not immediately detected. The manufacturer should be informed immediately in such cases so that an inspection of functional and operational safety can be conducted. Further safe operation of the clamping device can only be guaranteed in this manner.

Residual risks can emanate from insufficient rotary compensation, see § 6.2 No. e) EN 1550. This applies in particular where high speeds are involved, when machining asymmetrical workpieces or when using different collets. The chuck should be dynamically balanced with the workpiece mounted in accordance with DIN ISO 1940 to prevent any resulting damage.

The required clamping forces and/or permissible maximum speed for the chuck should be determined for a specific task in accordance with VDI Guideline 3106 (governing the determination of permissible speeds for rotary chucks (jawed chucks)). High centrifugal forces associated with special collets which, due to their design, are heavier or larger than the collets allocated to the clamping medium should be taken into consideration when determining the required clamping force and permissible speed.

VDI Guideline 3106 governing the determination of permissi­ble speeds for rotary chucks (jawed chucks) should always be consulted when using special collets/workpieces. The operator must rule out use of the clamping device at an ino-dinately excessive speed and, consequently, the generation of excessive centrifugal force if collets other than those inten­ded for this clamping device are used. A risk exists otherwise that the workpiece will not be adequately clamped. The clamping point must be within the clamping cone area. (Clamping points outside this area lead to collet and clamping device damage, thus posing a risk caused by workpieces being spun out).

The clamping device manufacturer and/or designer should therefore be consulted in all such cases.

Static clamping force measurement fixtures must be used in accordance with Guideline EN 1550 § 6.2 No. d) to check the service condition at regular intervals in accordance with the servicing instructions. Clamping force should therefore be in­spected after approx. 40 operating hours (i.e. regardless of clamping frequency).

Ifnecessary, special clamping force measuring collet chucks must be used. In the event that no suitable measuring devices such as, for instance, pressure measuring cell can be obtained, a torque check must be carried out using a clamped plug gauge.

So as to protect the operator against ejected parts and in line with DIN EN 12415 a separating protective equipment must be fitted to the machine tool, the resistance capability of which is specified in so--called resistance classes. Should new clamping sets be used on the machine, their approved suitability must first be checked. This also includes clamping sets and/or parts thereof manufactured by the user himself. This approved suitability is influenced by the resistance class of the protective equipment, the mass of the possible ejected parts (determined by calculation or weighing), the max. possi­ble chuck diameter (measure) as well as the max. possible speed of the machine. In order to reduce the possible impact force to the permissible value, the permissible mass and RPM must be determined (e.g. enquiry at the machine manu facturer) and then the max. RPM of the machine restricted (if required). However, the parts of the clamp set (e.g. collets, workpiece supports etc.) should be designed to be as light as possible.