Model RG Linear Drives for Reciprocating Motion Applications
Technical Information
Notes on Operation of Series RG and ARG / KI and AKI
Contents:
- Shaft material
- Shaft rotation
- Reversal
- Pitch setting
- Payload with separate carriage
- Vertical applications
- Stopping on a rotating shaft
- Traversing characteristics
- Synchronization of processes
- Operating temperature
- Maintenance
1.1. Basic requirements
Uhing linear drives must only be used in conjunction with induction-hardened, ground and finished steel shafts.
Minimum requirements:
- Surface hardness: 50 HRC
- Diametral tolerance: h6
- Out-of-roundness: no more than half the diameter variation permitted according to ISO tolerance h6
- Concentricity tolerance (DIN ISO 1101): < 0.1 mm/m
- Surface roughness: roughness height rating (DIN 4768 T.1) Ra: < 0.35 µm
Standard shafts:
Material similar to Cf 53, Mat. No. 1.1213, surface-hardened by induction, 60-64 HRC
Rust-proof shafts:
Material X 40 Cr 13, Mat. No. 1.4034, surface-hardened by induction, 51 - 55 HRC
Rust- and acid-proof shafts:
Material X 90 CrMoV 18, Mat. No. 1.4112, surface-hardened by induction, 52 -56 HRC
- All ground and superfinished
- Surface roughness: roughness height rating (DIN 4768 T.1) Ra: < 0.35 µm
- Diametral tolerance: h6
- Out-of-roundness: no more than half the diameter variation permitted according to ISO tolerance h6
- Concentricity tolerance (DIN ISO 1101): < 0.1 mm/m
As above but with a concentricity tolerance (DIN ISO 1101) < 0.03 mm/m
1.4. Leading end chamfer
The leading end of the shaft must be chamfered to avoid damage to the rolling rings when screwing the linear drive onto the shaft.
To facilitate screwing the shaft into the drive, make sure it is screwed in on the correct side (opposite the pressure screw).
For drives of the Kl and RG4-15/20/22/30-2 series, the entry side is not specified.
The mechanical reversal of the rolling ring drives depends on the direction of rotation. The reversing mechanism only works when the drive is operated with the direction of rotation specified in the order (except for feature D).
When the direction of rotation is changed, the pitch symmetry must be checked and, if necessary, readjusted.
3.1. Instantaneous reversal (feature M)
Mode of operation: When the drive makes contact with a traversing end stop, the springs in the snap-action switching mechanism are loaded and abruptly transmit their energy to the reversal mechanism after the dead centre has been passed.
To operate the reversal mechanism, a minimum traversing width of approx. one shaft diameter is required (depending on the pitch).
The reversal time also depends on the pitch (see Design, Fig. 2). Consequently, there is a slight increase in the traversing width when the pitch is increased (and a decrease when the pitch is reduced).
The traversing width is also affected when the speed is varied by a significant change in the shaft speed while the pitch remains unchanged. The drive then travels different distances during the reversal time.
Drive speed increases = increase in the traversing width.
Drive speed decreases = decrease in the traversing width.
3.2. Reversal slowdown (feature V)
Mode of operation: Shortly ahead of the point of reversal, an additional roller lever makes contact with a V-shaped slowdown cam and is thus swivelled. This swivel action reduces the set pitch as the drive approaches the point of reversal so that the following instantaneous reversal occurs at a greatly reduced traversing speed.
As a result of the reversal slowdown, the forces of gravity are reduced, allowing high traversing speeds to be applied without slipping.
The reversal slowdown mainly depends on the distance travelled. Changes in pitch do not affect the traversing width.
The pitch is the distance travelled per revolution of the shaft. With Uhing rolling ring drives, the pitch is variable between nearly zero and a specified maximum value. The pitch can be set when the drive is stopped or when the drive is in motion.
The following pitch setting options are available:
Kinemax:
Self-locking knob for continuous adjustment.
RG feature C:
Serrated 50-step scale covering the full pitch range. (RG 20/22/30: 100 steps)
RG feature S:
Set screws for continuous adjustment of the pitch, allowing the pitch to be separately set for each direction.
RG feature Z:
Worm gear drive for continuous adjustment of the pitch. Remote control from the bearing block possible.
Note:
With the exception of feature S, the pitch is generally set for both directions of travel. The difference in pitch of the two directions is limited to a maximum of 1 % at the factory.
5. Payload with separate carriage
If rolling rings are used to move payloads with a separate carriage, the coupling must be designed to compensate any misalignment between the drive shaft and the carriage.
In addition, it must be ensured that the distance between the point of connection and the drive is as short as possible as torques affect the thrust force of the drive.
Therefore, optimum couplings are torque-free as shown in Fig. 2 and Fig. 3.
Coupling connection at the front side of the drive
Fig. 2
Coupling connection at the side of the drive
Fig. 3
Heed the direction of action of the load and the position of the pressure adjusting screw to avoid a drop in the thrust force. (Does not apply for Kl3-15-4 and RG4-15/20/22/30-2.) In the installation position shown, there is an increase in the thrust force when the drive moves up the shaft.
When using a release lever, make sure that the load cannot drop in an uncontrolled manner before operating the release lever. Danger of injuries!
7. Stopping on a rotating shaft
Rolling ring drives fitted with slowdown cams (feature V) or control levers (features H, K) can be brought to a standstill (pitch setting "0") without having to stop the shaft if they are set up accordingly. This may be necessary when the drive is to be used as a feed mechanism and is required to wait for a start signal at one or at both ends of the traversing stroke. Intermediate stop positions between the end stops are also possible. For a positioning accuracy greater than ±1 mm, slowdown cams are suitable. For a positioning accuracy up to ±1 mm, the control lever is required.
To protect the shaft, we recommend that the shaft drive should be switched off if the standstill time exceeds 5 s and the maximum thrust is set. The standstill times can be extended if the shaft speed is low and the thrust is reduced. Please contact us if necessary.
By using a roller lever that makes contact with cams arranged along the traversing path, the pitch - and thus the speed - can be matched to the most varied requirements, the distances travelled being exactly repeatable.
9. Synchronisation of processes
Drives fitted with set screws (feature S) make it possible to exactly match the speed to already existing processes, such as cutting of continuously fed materials by travelling cutting devices. If the drive shaft and the material feed have a common drive, synchronisation is maintained even if the material speed varies.
Permissible temperature range: -10°C to +80°C. Special types for other temperatures are available on request.
For the lubrication of the shaft, normal commercially available MoS2-free roller bearing greases can be used (e.g. SKF Alfalub LGMT 2, Shell Alvania R2 or G2, Esso Beacon 2, BP Energrease LS2).
Procedure:
Clean the shaft and spread the grease as thinly as possible using a piece of cloth.
Lubricate the reversal mechanism, in particular the springs, using high-viscosity machine oil (SAE 90).
Frequency:
Weekly. Shorter intervals are recommended if the operating conditions are particularly demanding, e.g. if the drive must stop on the rotating shaft, if the drive is heavily soiled or if the operating temperature exceeds 80°C.
