Changing from cam followers
Hi folks
been a while since i've been here and also able to play with something new. We have a small machine that operates with a small motor driving a shaft at 4 RPM. There are a few single lobe cams on the shaft and there are ball bearing followers they are acting on. The part the followers are on, i'll call lifters, are solid an act on a spring that acts on a part being squeezed or clamped. The force is very low and buffered by the springs. I'd like the eliminate the bearings and maybe have the cam lobes directly act on the lifters but have their path sort of off centre so the lifter part turns when the cam wipes across the face lessening the friction. this is a NON lubricated application so all the parts are dry. The units already produced are already lasting 20 or 30 years and the bearings are replaced as wear items at least twice in that time. Any other broken or worn parts in this system are an anomaly.
I'd like to try and predict what the results will be from this change and ways to mitigate what could be excessive wear. like hard chrome or Teflon coatings for example?
URGENT: Rotor Dynamic balancing
Dear All,
We have a 90kW electrical motor. we overhaul the motor by replacing the bearing, dust seals, stator cleaning...
this was done because of bearing damage.
The stator and stator shaft seems to be OK without any crack, wear or damage.
Could you please advise whether a dynamic balancing for the rotor is needed or not?
when such balancing is neede?
thank you in advance.
How do i calculate the strength of a friction hinge?
Dears,
I am planning to use a single friction hinge at the center of the door. The door height is 7 inches and length is 17 inches. Weight of the door is 4.5 pound. Length of the hinge is 3.2 inches and pin diameter is .230 inches. How do i calculate if the hinge is good enough for the application?
Rack & Pinion versus Lead/ball Screw
Hi all,
Firstly I apologize if this has been posted before, but I am looking for a comparison between R&P and LS on the basis of linearly produced force. I find it difficult to get the right answers since most posts refer to these system being used in CNC machines for positioning.
I am working on a project that requires a linear force of 800N. Travel distance of 130mm, desired speed 30mm/s. When using the following equations for each device, I get the torque required for such an output.
R&P:
T=F.r
F=800N
r=0.004
T = 3.2N.m
Ball screw:
T=F.L(lead)/(2.pi.0.9)
F=800N
L=8
T=1.13N.M
I used a diameter of 8mm and a lead of 8 to ensure the same travel distance per revolution. From this is it safe to say that a ball screw would be the best solution since it requires less torque from the motor? Does the mass moment of inertia of the screw equate to a considerable increase in torque required, that should be accounted for?
This is only a rough estimate to decide which of the two would work best for the application.
Your input would be appreciated.
Thank you.
How to apply a constant, gradually increasing load to a machine.
Hello. I'm an amateur engineer that has dabbled in just about everything. Electronics, computer engineering, wood, metal, plastic, the list goes on and on. But I'm having trouble figuring out how to design my newest project. Sure, I do have ideas, but they're not elegant.
The machine is a piece of equipment that will deliver a lateral linear force against a person to test their resistance. It is being designed for use with the martial art Wing Chun to test the player's stance. A proper stance will allow the practitioner to withstand hundreds of pounds of force incoming from in front of them without moving backward.
I have absolutely no problem transforming a downward force into a lateral force to push a platform against the player's stance. The point where I encounter difficulty is that I don't just want a constant force, I would like to develop the machine as a sort of strain test; I would like to find a way to gradually increase the force applied to the player in such a way that it can still be resisted, but that it will increase until the player fails the test.
My original idea was to connect a reservoir to a pulley, and, as you fill the reservoir, it increases the load, which is turned into lateral force against the player. The problem with this is that I want the machine to be easily reset, so that the test can be run repeatedly. I'm having trouble figuring out a way to increase the load gradually in a way that would be smooth and still be easy enough to reset to ready position.
If anyone has any ideas, I'm open to absolutely any suggestions, even a redesign from the ground up.
A2-70 Material for Washers
Hello to all,
If anyone is familiar with this...
Is it correct for a DIN125A washer to be made from A2-70 material?
DIN 125, only refers to A2, and not -70 as a codification method.
Although i have searched the web and found sources that confirm the use of A2-70
but i have also read that A2-70 should only be mentioned for screws,nuts and bolts.
Then again i wonder, why not construct washers from A2-70? Is it an abbreviation matter?
Thank you in advance.
Crown and spur gears
I have to make a small reversing gear assembly and i've proposed it to use 2 spur gears and a crown face gear. Now I have to do the models but i'm not finding much information of the modeling of a crown gear and how to make the teeth? Am I making it too complicated? I have it in solidworks now but it doesn't look right.
Edit: Actually I know how to make teeth. but how do I determine the shape? I just took the tooth form from the spur gears and cut them across the crown shape.
The Journal Bearing Temperaure Raising During Rainy
Dear All
I'm operating a compressor 3rd stages. During normal operation Journal bearing temperature of LP/IP Stage were rasing from 98 degree to 105 degree at alarm set point. These event happened while rainy then back to normal once stop.
Could you pls help to advise me the root cause & preventive action to resolve this problem.
Thanks you all.
Horizontal Rod Size Required
Many, many years ago I graduated college as a Mechanical Engineering Technologist but my career path took me elsewhere. I therefore can use and comprehend most of the "tools of the trade" but I'm very rusty in that usage. I therefore don't feel fully confident in my own calculations and would like some input.
I want to use a 12" long Stainless Steel solid rod to support approximately 200 lbs of weight equally distributed between two mounted bearings on each end with the rod itself only supported in the center.
In addition to the rod supporting the weight, it needs to remain straight enough that the bearings do not bind due to a bend in the rod.
For unrelated reasons the rod cannot exceed 2.375" diameter But I'm hoping the actual required size is much less than that.
I'd appreciate either an answer with some supporting calculations or a link to somewhere the info can be found.
Siemens plc- lost back-up and unable to access the programs.
i need an opinion or possible solutions related with the PLC Siemens. presently i have a chilled water pumps with control panel integrated with PLC, MHI and VFD. the system control are designed and proven to be in-line with the project specifications. but i have an issue about accessing the PLC program. I've try to approached the supplier and asked if they have the records of the installed unit but unfortunately they don't have it, even the local engineering dept lost the backup and therefore no body can access the PLC. now i am looking for a solution to have a PLC password in order to copy the program or either to be enable to access the PLC again.
QuestionS:
1. is it possible again to retrieve or replace the unknown PLC password?? if so, is it necessary to pullout the PLC hardware and connect to the PC or it can be done even without pulling-out the hardware?? any suggestion please!!
2.if the existing PLC password is not possible to replace or retrieve. it is possible to extract the program or data of it and import to the new PLC ???