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DS‐58[20] Absolute Rotary Electric Encoders™ Mechanical Installation Guide Document No. : DS‐58[20] mechanical installation guide Version: 0.1, July 2009 Netzer Precision Motion Sensors Ltd. Misgav Industrial Park, P.O. Box 1359 D.N. Misgav, 20174 Israel Tel: +972 4 999 0420 Fax: +972 4 999 0432 www.netzerprecision.com global‐
[email protected]
The DS‐58[20] Electric Encoder™ is semi‐modular, i.e. its rotor and stator are separate, but the rotor is captive inside the stator. Both rotor and stator are supported by the host machine at their one end and loaded – or clamped, at their other end. The encoder can be mounted either on a middle of a machine shaft, or at the end of a shaft. A step can be machined to provide an axial support area for the rotor– as in Figure 1, or the shaft can be smooth and support the rotor with the aid of a C‐ring as shown in Figure 7a. The axial clamping force on the rotor can be provided by a factory supplied special wave springs or through the loading of other machine elements, such as ball bearings. The (encoder) stator is supported axially at its circumference and is secured to the host machine by means of three factory supplied (encoder) stator clamps. The stator is supported radially by a recess in the host machine and is constructed such that its radial contact with the machine is restricted to three segments 120° apart as in Figure 1. In order to meet the recommended axial tolerance, despite potential manufacturing errors in the host machine, special compensation shims are available to be placed underneath the stator, or rotor. In addition, a special gauge can be obtained to assist the selection of the proper shims. Figure – 1 Overview Installation procedure Figure 2 shows the encoder clamps (factory supplied with the encoder) and their engagement slots in the encoder. Figure 3 shows the recess in the host machine which supports the stator both axially and radially, it also shows the contact areas of the rotor and stator. The recommended axial distance between surfaces A and B (Figure 3) is 1.5 ± 0.05mm; this is in order to center the rotor between the stator’s transmitter and receiver plates. Axial misalignment will influence the raw sine/cosine output signals of the Fine channel – see AN‐2; however, the accuracy and resolution will be nearly the same ‐ as long as the rotor is within ±0.2mm from the center and does not touch the stator plates. www.netzerprecision.com
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Mechanical installation of the encoder involves the following steps: Step 1: Validate the axial distance between the machine support areas A and B. Since the actual distance between surfaces A and B includes the host machine tolerance buildup it is easier to meet the requirement using compensation shims as follows: 1. Measure the axial distance h between surfaces A and B, If 1.45mm
1.55mm: put a rotor compensation shim (MP‐DS‐58‐SPR0.1 or MP‐DS‐58‐SPR0.05) between the rotor bottom and surface B. 3. If h < 1.45 mm: put a stator compensation shim (MA‐DS‐58‐SPC0.1 or MA‐DS‐58‐SPC0.05) between the stator peripheral rim and surface A. Note 1: The rotor compensation shims are ring shaped, the stator compensation shims are shown in Figure 5 ‐ both are available in thicknesses of 0.1mm and 0.05mm. Note 2: The above measurement can be eased using the special gauge (catalog # MP‐DS37‐GAU‐01). The gauge is mounted on the machine shaft and is rotated underneath the indicator plunger between two positions while the indicator mounting is stationary. Note 3: The electrical integrity of the installed DS‐58 with analog SIN/COS outputs can be validated as detailed in application note AN‐02. Note 4: Standard DS encoders are insensitive to ESD and parasitic capacitive coupling from adjacent AC voltages, however, it is recommended to allow a discharge path of no more than several tens of kΩ between the machine shaft and the electronics’ ground, not leaving it electrically floating. Step 2: The encoder clamps are secured by M2 screws on a φ42mm bolt circle. 1. Screw the encoder clamps. Do not forget to include compensation shims, if needed. 2. Unscrew each encoder clamp slightly and make its flat side face the rotation axis to allow the insertion of the encoder (stator) into the recess. 3. Turn the encoder in the recess as necessary, to align its slots with the encoder clamps. 4. Tighten the encoder clamps with a torque of 0.2 Nm to fix the stator – as in Figure 1.
Figure 2, Stator Clamps & Slots
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Figure 3, Contact surfaces
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Step 3: Clamp the rotor against a step, or a C‐ring on the machine shaft (surface B in Figure 3) e.g. using any of the means shown in Figure 6. The clamping force should be 0.3 Nm. Figure – 5, compensation shims Figure – 4, amplitude
(b) End of shaft Figure 6, Rotor clamping options
(a) Steeped shaft
(b) Smooth shaft – using “C” ring Figure 7, Rotor support options
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Mechanical dimensions
DS‐58[20] with Connector
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DS‐37, mechanical installation guide 5
DS‐58 , Encoder clamp With bolt M2 Cat No. EAMP7049
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DS‐58 Rotor shims 0.1 mm Cat No. MP‐DS37‐SPR0.10 0.05 mm Cat No. MP‐DS37‐SPR0.05
DS‐58 Stator shims 0.1 mm Cat No. MP‐DS37‐SPC0.1 0.05 mm Cat No. MP‐DS37‐SPC0.05
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DS‐58 Measurement gauge Cat. No. MP‐DS37‐GAU01 DS‐58 Retaining ring Cat. No. MP‐00068
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1
2
3
4
5
6
63 ±0.1 A
A
6 5 4 3 2 B
1
B
+0.05
55 0 25 min 23 0
20 - 0.05 M6
3 X M2
8
5 X 120 C
1.5 ±0.05
9 ±0.1
2.50 min
C
Assembly Scale 3 : 2
Host system mounting details
D
NO. 1 2 3 4
PART NAME Host shaft Host base DS-58-20 Encoder Encoder clamp
CATALOG NO. EAMP7049
QTY 1 1 1 3
5
Washer 4.3 DIN 9021
1
6
Screw M6X10 DIN 7984
1
1
2
Title:
DS-58-20 Installation: Shaft end, stepped shaft
Note: Keep clearance of at least 1.0 mm on all non-mounting surfaces 3
Date: July 09 SHEET 1 OF 1
4
A4
Version: 0.1 SCALE:
1:1
Dimensions : mm
5
