Oak, motorized (24V DC) PLC shift gears (3 ratio's)possible?

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cis
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Joined: Mon Jun 21, 2021 5:54 pm
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Oak, motorized (24V DC) PLC shift gears (3 ratio's)possible?

Post by cis »

On this forum i have not found detailed information about a motorized (24V DC) automatic gear shift.
The lathe i'm doing a retrofit has a motorized (24V DC) linear actuator, a 3 speed gearbox with low speed= 14-275 rpm, mid= 40-785 rpm, high speed= 125-2500 rpm. The main motor is a 7,5kW with a Vsd from Mitsubishi type Freqrol A200. The speed regulation with a 0-10Volt signal is working fine with the Oak bard. The main spindlemotor can run 6000rpm maximun at 200Hz.
The gearbox has a motorized linear actuator.
The actuator is a SKF, type CAT33-24Volt DC,(low speed C24CW), with limit switches CAXC33.
Here you can find the catalogue, http://www.lmotion.ru/cataloguespdf/skfla.pdf, page 23-29.
This actuator is without encoder, without potentiometer.
Here you can find technical details: https://docs.rs-online.com/abd0/0900766b81692722.pdf
The motor of the actuator has a current consumption of 5Amp. See page 7.
Pictures actuator in the attachment.
The way it works with the original FANUC 20T was as follows: simpilifie explained.
The gearbox has 3 ratios, gearbox is driven with a poly flat belt by the main motor of 7,5kW, controlled with a VFD.
Gear shifter cannot move to required position unless gears are aligned to move.
So it is normal practice to oscilate the spindle (for/rev) while gear shifting (command value should be slow like 5 to 10 rpm).
The actuator must be only enabled when spindle index is off (spindle not enabled for oscillation).
If no confirmation of the required gear position then it should repeat the spindle index sequence. When the gears are not in the correct position, the plc will detect this, plc logic change the rotation direction of the actuator motor for a short time, plc logic will start to oscilate the spindle slowly for a short time, plc will repeat this process until the gears are in the correct position. This is a known system on industrial lathes like Colchester, Nardini, Schaublin, Harrison and other lathes with a Fanuc 20T controller.
How can i get the automatic motorized gear shift done? On the Centroid website is a schematic filename S14667.TC, but tihs is for a 3 phase motorized shifter. Must the Plc logic be modified? Thx in advance.
Attachments
SKT actuator CAT33 24V DC.jpeg
SKF actuatorCAT33 24V DC cover removed.JPG
cncsnw
Posts: 2278
Joined: Wed Mar 24, 2010 5:48 pm

Re: Oak, motorized (24V DC) PLC shift gears (3 ratio's)possible?

Post by cncsnw »

A reversible motor is a reversible motor, whether it is a 3-phase AC motor or a DC motor. In either case, you are going to use PLC outputs to close either a run-forward or a run-reverse relay or contactor.

It is up to you to supply and wire the forward and reverse contactors so that the PLC outputs can run the gear-shift motor as needed.

There is at least some chance that a PLC program someone at Centroid wrote for one of the Baron-Max KL-series lathes would work for your system. If not, then you will need to modify the PLC program, or hire someone to do it for you.
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