LVDT???
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Posts: 46,084
Leroy,
Thanks for the input. We would prefer to use multiple proximity
switches... but the customer is always right (unless we can convince them
of a better solution)!
Let me explain the application a bit more. The cylinder is to be used to
clamp three types of parts -- all of different heights. The customer
doesn't want to have to set the machine up for each individual part and
suggested an LVDT for automatic part recognition. I guess I need to talk
to our mechanical guy to find out the range in part heights. I am
guessing about 2 inches of the overall stroke is all we would really be
concerned about. Is this doable? How much range does a typical LVDT
have? 1/2, 1, 3, 10 inches?
When you say 'sophisticated electronics' are needed to interface to a
stamp, I assume its is not as easy as feeding an analog signal into an
A/D converter?
Regards,
Aaron
PS: Isn't Loveland around Cincinnati? I am in Dayton.
On Sat, 11 Aug 2001 15:24:06 -0400 "Leroy Hall, Senior" <leroy@f...>
writes:
> An LVDT is used to measure very small distances on machine tools.
> They can sense distances in the tenths of one thousand of an inch.
Some
> perspective here. A human hair is usually somewhere around 3
> thousands (.003) This device could measure them like you would use a
tape
> measure on a room. They would be very difficult, with out some pretty
> sophisticated electronics, to interface with the stamp. What I
> would suggest is Proximity switch for your stated application. They
are
> often used they and are much cheaper. Easier to interface too, as they
> usually provide a logic 24 VDC or 120 VAC output signal that would
> be easy to interface to the stamp.
>
> BTW air cylinders are not usually sensed as to position. Air is
> compressible and sensing position on this type of device would be
> very difficult. Depending on resolution required, several prox
switches
> might be used. Air cylinders typically are sensed at either end of
> their stroke.
Thanks for the input. We would prefer to use multiple proximity
switches... but the customer is always right (unless we can convince them
of a better solution)!
Let me explain the application a bit more. The cylinder is to be used to
clamp three types of parts -- all of different heights. The customer
doesn't want to have to set the machine up for each individual part and
suggested an LVDT for automatic part recognition. I guess I need to talk
to our mechanical guy to find out the range in part heights. I am
guessing about 2 inches of the overall stroke is all we would really be
concerned about. Is this doable? How much range does a typical LVDT
have? 1/2, 1, 3, 10 inches?
When you say 'sophisticated electronics' are needed to interface to a
stamp, I assume its is not as easy as feeding an analog signal into an
A/D converter?
Regards,
Aaron
PS: Isn't Loveland around Cincinnati? I am in Dayton.
On Sat, 11 Aug 2001 15:24:06 -0400 "Leroy Hall, Senior" <leroy@f...>
writes:
> An LVDT is used to measure very small distances on machine tools.
> They can sense distances in the tenths of one thousand of an inch.
Some
> perspective here. A human hair is usually somewhere around 3
> thousands (.003) This device could measure them like you would use a
tape
> measure on a room. They would be very difficult, with out some pretty
> sophisticated electronics, to interface with the stamp. What I
> would suggest is Proximity switch for your stated application. They
are
> often used they and are much cheaper. Easier to interface too, as they
> usually provide a logic 24 VDC or 120 VAC output signal that would
> be easy to interface to the stamp.
>
> BTW air cylinders are not usually sensed as to position. Air is
> compressible and sensing position on this type of device would be
> very difficult. Depending on resolution required, several prox
switches
> might be used. Air cylinders typically are sensed at either end of
> their stroke.
Comments
helps..
http://www.rdpelectrosense.com/displacement/lvdt/lvdt-principles.htm
Understand about the customer being right <GRIN> yep it's a fact! I am
sure that range is available see above link. They make interface units
for their LVDT's as well. I would need to see the application to
determine what would be a good solution to the 'clamp at different
heights problem'. Is the air cylinder doing positioning or the heights
determined by the part and the cylinder is just clamping it at it's
height?
Yes, Loveland is near Dayton!!
Hope this helps,
Leroy
agarb@j... wrote:
>
> Leroy,
>
> Thanks for the input. We would prefer to use multiple proximity
> switches... but the customer is always right (unless we can convince them
> of a better solution)!
>
> Let me explain the application a bit more. The cylinder is to be used to
> clamp three types of parts -- all of different heights. The customer
> doesn't want to have to set the machine up for each individual part and
> suggested an LVDT for automatic part recognition. I guess I need to talk
> to our mechanical guy to find out the range in part heights. I am
> guessing about 2 inches of the overall stroke is all we would really be
> concerned about. Is this doable? How much range does a typical LVDT
> have? 1/2, 1, 3, 10 inches?
> When you say 'sophisticated electronics' are needed to interface to a
> stamp, I assume its is not as easy as feeding an analog signal into an
> A/D converter?
>
> Regards,
> Aaron
>
> PS: Isn't Loveland around Cincinnati? I am in Dayton.
>
> On Sat, 11 Aug 2001 15:24:06 -0400 "Leroy Hall, Senior" <leroy@f...>
> writes:
> > An LVDT is used to measure very small distances on machine tools.
> > They can sense distances in the tenths of one thousand of an inch.
> Some
> > perspective here. A human hair is usually somewhere around 3
> > thousands (.003) This device could measure them like you would use a
> tape
> > measure on a room. They would be very difficult, with out some pretty
> > sophisticated electronics, to interface with the stamp. What I
> > would suggest is Proximity switch for your stated application. They
> are
> > often used they and are much cheaper. Easier to interface too, as they
> > usually provide a logic 24 VDC or 120 VAC output signal that would
> > be easy to interface to the stamp.
> >
> > BTW air cylinders are not usually sensed as to position. Air is
> > compressible and sensing position on this type of device would be
> > very difficult. Depending on resolution required, several prox
> switches
> > might be used. Air cylinders typically are sensed at either end of
> > their stroke.
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject and Body
of the message will be ignored.
>
>
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--
*******************************************************
* Leroy Hall *
* 317 Cherokee Drive *
* Loveland, Ohio - USA 45140-2404 *
*******************************************************
* Phone: (513) 697-7539 *
* Cell : (513) 300-8632 *
* Email: leroy@f... *
* Home page URL: http://home.fuse.net/leroy/ *
* Resume URL: http://home.fuse.net/leroy/resume.htm *
*******************************************************
* Leroy Hall *
* 317 Cherokee Drive *
* Loveland, Ohio - USA 45140-2404 *
*******************************************************
> to our mechanical guy to find out the range in part heights. I am
> guessing about 2 inches of the overall stroke is all we would really be
> concerned about. Is this doable? How much range does a typical LVDT
> have? 1/2, 1, 3, 10 inches?
Keep going! :-) I used some on a couple of underwater ploughs I built (&
redesigned). They had about 3 ft travel. There is a picture of the plough at:
http://www.geocities.com/SiliconValley/Vista/8552/
but you probably can't see much. The LVDT was inside a hydraulic ram
that was used to push the ploughshare down, so we could tell what depth
trench we were digging, and therefore what depth we were burying the
fiber-optic telephone cable.
> When you say 'sophisticated electronics' are needed to interface to a
> stamp, I assume its is not as easy as feeding an analog signal into an
> A/D converter?
Yes, that's about it. I used a fixed DC voltage in, and got a variable voltage
out. Fed that into a Red Lion panel meter which gave a visible reading in
LED numbers and allowed calibration parameters to be stored in the
meter, giving a conversion from voltage to burial depth (maximum of 2
metres). The Red Lion meters also have RS-422 output, so I could link all
3 meters up (Burial, Pitch & Roll) & send the data through an RS-232
converter into a notebook. The notebook logged all the parameters and
was also interfaced into a GPS to cross-reference the above data with
position.
Dave
>Let me explain the application a bit more. The cylinder is to be used to
>clamp three types of parts -- all of different heights. The customer
>doesn't want to have to set the machine up for each individual part and
>suggested an LVDT for automatic part recognition. I guess I need to talk
>to our mechanical guy to find out the range in part heights. I am
>guessing about 2 inches of the overall stroke is all we would really be
>concerned about. Is this doable? How much range does a typical LVDT
>have? 1/2, 1, 3, 10 inches?
>When you say 'sophisticated electronics' are needed to interface to a
>stamp, I assume its is not as easy as feeding an analog signal into an
>A/D converter?
>
How about a pneumatic damper actuator as used in hvac appplications? There
are transducers that change a 4-40ma, 1-10v, 1-20v, or pwm signal and convert
it to 1 to 15 psi at the actuator.
Carl
the part, measuring the travel does not matter. If you supply a fixed
pressure to the cylinder, it will generate the same force at the top or
bottom of its travel. The only thing you may want to do is monitor the
travel speed so you don't cram the clamp into the part too hard.
Original Message
> >Let me explain the application a bit more. The cylinder is to be used to
> >clamp three types of parts -- all of different heights. The customer
> >doesn't want to have to set the machine up for each individual part and
> >suggested an LVDT for automatic part recognition. I guess I need to talk
> >to our mechanical guy to find out the range in part heights. I am
> >guessing about 2 inches of the overall stroke is all we would really be
> >concerned about. Is this doable? How much range does a typical LVDT
> >have? 1/2, 1, 3, 10 inches?
> >When you say 'sophisticated electronics' are needed to interface to a
> >stamp, I assume its is not as easy as feeding an analog signal into an
> >A/D converter?
> >
>
> How about a pneumatic damper actuator as used in hvac appplications?
There
> are transducers that change a 4-40ma, 1-10v, 1-20v, or pwm signal and
convert
> it to 1 to 15 psi at the actuator.
machine which part it is now working on.
Robert
>
Original Message
> From: Rodent [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=gTBpDztdrsOni476W7rRkIO1-1af-9I_HQtFz1jpADH-Q1591-cJG_KhZ9OM2qjbH2k6pVpRAJdw56v1Qeo]daweasel@s...[/url
> Sent: Sunday, August 12, 2001 11:56 AM
> To: basicstamps@yahoogroups.com
> Subject: Re: [noparse][[/noparse]basicstamps] LVDT???
>
>
> Correct me if I'm wrong, but if the cylinder is pressing directly down on
> the part, measuring the travel does not matter. If you supply a fixed
> pressure to the cylinder, it will generate the same force at the top or
> bottom of its travel. The only thing you may want to do is monitor the
> travel speed so you don't cram the clamp into the part too hard.
>
>
Original Message
>
> > >Let me explain the application a bit more. The cylinder is to
> be used to
> > >clamp three types of parts -- all of different heights. The customer
> > >doesn't want to have to set the machine up for each individual part and
> > >suggested an LVDT for automatic part recognition. I guess I
> need to talk
> > >to our mechanical guy to find out the range in part heights. I am
> > >guessing about 2 inches of the overall stroke is all we would really be
> > >concerned about. Is this doable? How much range does a typical LVDT
> > >have? 1/2, 1, 3, 10 inches?
> > >When you say 'sophisticated electronics' are needed to interface to a
> > >stamp, I assume its is not as easy as feeding an analog signal into an
> > >A/D converter?
> > >
> >
> > How about a pneumatic damper actuator as used in hvac appplications?
> There
> > are transducers that change a 4-40ma, 1-10v, 1-20v, or pwm signal and
> convert
> > it to 1 to 15 psi at the actuator.
>
>
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the
> Subject and Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
>
regulataed pressure) to hold the part in place.
Each one of the parts sits on a the same, fixed surface. The parts are
different heights, so when we clamp we just need to sense how far the
cylinder has extended when it reaches the part. This will let the
software 'decide' which part is being clamped and will automatically set
up the machine for the rest of the process.
On Sun, 12 Aug 2001 10:56:01 -0500 Rodent <daweasel@s...> writes:
> Correct me if I'm wrong, but if the cylinder is pressing directly
> down on the part, measuring the travel does not matter. If you supply a
> fixedpressure to the cylinder, it will generate the same force at the
top
> or bottom of its travel. The only thing you may want to do is monitor
> the travel speed so you don't cram the clamp into the part too hard.
>
> The cylinder bore is sized to furnish the clamp force we need (at a
> regulataed pressure) to hold the part in place.
>
> Each one of the parts sits on a the same, fixed surface. The parts are
> different heights, so when we clamp we just need to sense how far the
> cylinder has extended when it reaches the part. This will let the
> software 'decide' which part is being clamped and will automatically set
> up the machine for the rest of the process.
I saw the info on the Bimba cylinders at work today. It's called a
"Position Feedback Cylinder" and has a linear pot (100K?) built into the
cylinder shaft. It is a little pricey at $250'ish and the controller is
about the same. BUT you could probably use the Stamp and read the pot to
determine the difference in the parts without having to fool with the
controller.
HTH
--
Doyle Whisenant
mechanic@s...
http://mechanic.webjump.com
(of course "best" will be subjective and greatly argued.).
A. Environmental conditions. (dirty or clean, noisy(EMI), harsh, wet, ect.)
B. Range of part sizes. (What is the Minimum and Maximum height difference
between the parts? <1mm, >1cm)
C. Budget!!
D. Time to delivery
If the difference in height between the parts is significant say 1/4 inch or
more then a magnet and some reed switches (or hall effect) would do it. You
could get even tighter spacing if you went with thru-beam IR.
If you need millimeter or less resolution then you press into the higher
cost arena quickly, DRO's, drop gauges, ect.
I've used the drop gauge with mini recorder often for quick measurement data
collection it is the simplest and fastest for me, although the more
expensive (~$200 USD for new)
Best regards,
Mike Witherspoon
Original Message
From: agarb@j... [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=bxoOhuOHwLiRzQ6h8C6V07MQ6co7kc_Vf6eMCGiS15Kyri_6LoCftao3hyKO2vzbjj5tvf4]agarb@j...[/url
Sent: Monday, August 13, 2001 4:06 PM
To: basicstamps@yahoogroups.com
Subject: Re: [noparse][[/noparse]basicstamps] LVDT???
The cylinder bore is sized to furnish the clamp force we need (at a
regulataed pressure) to hold the part in place.
Each one of the parts sits on a the same, fixed surface. The parts are
different heights, so when we clamp we just need to sense how far the
cylinder has extended when it reaches the part. This will let the
software 'decide' which part is being clamped and will automatically set
up the machine for the rest of the process.
On Sun, 12 Aug 2001 10:56:01 -0500 Rodent <daweasel@s...> writes:
> Correct me if I'm wrong, but if the cylinder is pressing directly
> down on the part, measuring the travel does not matter. If you supply a
> fixedpressure to the cylinder, it will generate the same force at the
top
> or bottom of its travel. The only thing you may want to do is monitor
> the travel speed so you don't cram the clamp into the part too hard.
To UNSUBSCRIBE, just send mail to:
basicstamps-unsubscribe@yahoogroups.com
from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
> link all 3 meters up (Burial, Pitch & Roll) & send the data through an
RS-232
> converter into a notebook. The notebook logged all the parameters
> and was also interfaced into a GPS to cross-reference the above data
> with position.
Sounds like a cool project!
investigating/digesting all the info as well as pursuing some other
options as suggested...
Regards,
Aaron
On Sat, 11 Aug 2001 20:16:12 -0400 "Leroy Hall, Senior" <leroy@f...>
writes:
> I did a search on LVDT at www.goolge.com and found this. Hope it
> helps..
>
>
> http://www.rdpelectrosense.com/displacement/lvdt/lvdt-principles.htm
>
>
> Understand about the customer being right <GRIN> yep it's a fact!
> I am
> sure that range is available see above link. They make interface
> units
> for their LVDT's as well. I would need to see the application to
> determine what would be a good solution to the 'clamp at different
> heights problem'. Is the air cylinder doing positioning or the
> heights
> determined by the part and the cylinder is just clamping it at it's
> height?
>
> Yes, Loveland is near Dayton!!
>
>
> Hope this helps,
>
>
> Leroy
>
> agarb@j... wrote:
> >
> > Leroy,
> >
> > Thanks for the input. We would prefer to use multiple proximity
> > switches... but the customer is always right (unless we can
> convince them
> > of a better solution)!
> >
> > Let me explain the application a bit more. The cylinder is to be
> used to
> > clamp three types of parts -- all of different heights. The
> customer
> > doesn't want to have to set the machine up for each individual
> part and
> > suggested an LVDT for automatic part recognition. I guess I need
> to talk
> > to our mechanical guy to find out the range in part heights. I am
> > guessing about 2 inches of the overall stroke is all we would
> really be
> > concerned about. Is this doable? How much range does a typical
> LVDT
> > have? 1/2, 1, 3, 10 inches?
> > When you say 'sophisticated electronics' are needed to interface
> to a
> > stamp, I assume its is not as easy as feeding an analog signal
> into an
> > A/D converter?
> >
> > Regards,
> > Aaron
> >
> > PS: Isn't Loveland around Cincinnati? I am in Dayton.
> >
> > On Sat, 11 Aug 2001 15:24:06 -0400 "Leroy Hall, Senior"
> <leroy@f...>
> > writes:
> > > An LVDT is used to measure very small distances on machine
> tools.
> > > They can sense distances in the tenths of one thousand of an
> inch.
> > Some
> > > perspective here. A human hair is usually somewhere around 3
> > > thousands (.003) This device could measure them like you would
> use a
> > tape
> > > measure on a room. They would be very difficult, with out some
> pretty
> > > sophisticated electronics, to interface with the stamp. What I
> > > would suggest is Proximity switch for your stated application.
> They
> > are
> > > often used they and are much cheaper. Easier to interface too,
> as they
> > > usually provide a logic 24 VDC or 120 VAC output signal that
> would
> > > be easy to interface to the stamp.
> > >
> > > BTW air cylinders are not usually sensed as to position. Air is
> > > compressible and sensing position on this type of device would
> be
> > > very difficult. Depending on resolution required, several prox
> > switches
> > > might be used. Air cylinders typically are sensed at either end
> of
> > > their stroke.
> >
> > To UNSUBSCRIBE, just send mail to:
> > basicstamps-unsubscribe@yahoogroups.com
> > from the same email address that you subscribed. Text in the
> Subject and Body of the message will be ignored.
> >
> >
> > Your use of Yahoo! Groups is subject to
> http://docs.yahoo.com/info/terms/
>
> --
>
> *******************************************************
> * Leroy Hall *
> * 317 Cherokee Drive *
> * Loveland, Ohio - USA 45140-2404 *
> *******************************************************
> * Phone: (513) 697-7539 *
> * Cell : (513) 300-8632 *
> * Email: leroy@f... *
> * Home page URL: http://home.fuse.net/leroy/ *
> * Resume URL: http://home.fuse.net/leroy/resume.htm *
> *******************************************************
> * Leroy Hall *
> * 317 Cherokee Drive *
> * Loveland, Ohio - USA 45140-2404 *
> *******************************************************
>