Transcript Ball Screw and Ball Rail MiniMill An Alternate to the

The Standard MiniMill™
A small milling machine using ball
screws and linear rails
By: Roger Cortesi
[email protected]
http://pergatory.mit.edu/rcortesi/
Precision Engineering Research Group
Massachusetts Institute of Technology, Mechanical Engineering Department
Room 3-470
77 Massachusetts Ave.
Cambridge, MA 02139
Phone: (617) 253-1953
Fax: (617) 258-6427
http://pergatory.mit.edu/
Property of Roger Cortesi, MIT Precision Engineering Research Group. DO NOT COPY or TRANSMIT without written permission.
The Standard
MiniMill™
An Alternate to the original MiniMill™
By Roger Cortesi
MIT Mechanical Engineering
Precision Engineering Research Group
27 FEB 00
Property of Roger Cortesi, MIT Precision Engineering Research Group. DO NOT COPY or TRANSMIT without written permission.
The Modified MiniMill™
Is the original machine design. It uses linear motors for
motive power and air bearings for the linear guides.
The Standard MiniMill™
This machine is the same as the modified machine , but the
motive power is provided by ball screws. Ball Rails are the
linear guides.
The transition from the traditional technology in The Standard
MiniMill™ to the technology in The Modified MiniMill™ can
be done incrementally!!!
I.E. it is very easy to have a machine that is:
Powered by Ball Screws
Guided by Air Bearings
or
Powered by Linear Motor
Guided by Ball Rails
Property of Roger Cortesi, MIT Precision Engineering Research Group. DO NOT COPY or TRANSMIT without written permission.
Why The Standard MiniMill™
Using the traditional motive components
(ball screws and ball rails) is less of a
market risk than the linear motors and air
bearing version of the MiniMill™.
Property of Roger Cortesi, MIT Precision Engineering Research Group. DO NOT COPY or TRANSMIT without written permission.
The Standard MiniMill™ Features
• The same structural “L” shapes are used by
both the Standard and Modified MiniMill™s.
• The same “L” mold can be used for either
machine. Only the threaded insert patterns are
different.
Property of Roger Cortesi, MIT Precision Engineering Research Group. DO NOT COPY or TRANSMIT without written permission.
The Structural “L” for the Standard and
Modified MiniMill™s
The Standard MiniMill™
The Modified MiniMill™
Property of Roger Cortesi, MIT Precision Engineering Research Group. DO NOT COPY or TRANSMIT without written permission.
More Standard MiniMill™ Features
• All three axis use identical ball screws, ball
nuts and ball rails for cost savings.
• Depending on the customer’s accuracy and
price constraints, position sensing on the
standard MiniMill™ can be done by a
rotary encoder on the motor or a linear
position encoder on the carriages.
Property of Roger Cortesi, MIT Precision Engineering Research Group. DO NOT COPY or TRANSMIT without written permission.
Design Issues Still In Progress
• Axis motor selection
– Currently Maxon™ Motor is the most likely.
• Stiffness estimates for the Standard MiniMill™
– The Standard MiniMill™ should be much stiffer than the Modified
MiniMill™
• Determine required accuracy grades on ball screw and linear rails
and trucks
• Type and mounting locations for limit switches
• Type and mounting locations and type for bumpers
• Mounting hardware and locations for cable carriers
Property of Roger Cortesi, MIT Precision Engineering Research Group. DO NOT COPY or TRANSMIT without written permission.
Parts to Order From Star Linear™
Quantity Description
3
3
3
3
3
3
12
6
Single Nut 12x5 Rx2/5-3 w/ Flange
FEM-E-S
Fixed End Bearing ZKILN
Fixed End Pillow Block Unit ZKILN
Part
Notes
Number
1532-4-6013
1590-1-0600
1591-1-0620 May include bearings, need to
check
Floating End Bearing DIN 625
1590-6-0600
Floating End Pillow Block Unit DIN 625 1590-6-0620 May include bearings, need to
check
12 x 5 Rx2.5 Rolled Screw, Threaded TBD
Need to decide what tolerance
Length of 730 mm
grade (T5, T7, or T9)
No 15 Trucks
TBD
Need to decide Super, Steel, or
Al and which accuracy class (H
or N)
Size 15 Rails, 750mm Long
TBD
Need to decide what is the
needed accuracy class (UP,
SP, P, H, or N)
Property of Roger Cortesi, MIT Precision Engineering Research Group. DO NOT COPY or TRANSMIT without written permission.
A View of the Standard MiniMill™’s X Axis
Motor Mounted Here
Details TBD
Linear Position Encoder Not Shown
Property of Roger Cortesi, MIT Precision Engineering Research Group. DO NOT COPY or TRANSMIT without written permission.
A View of the Standard MiniMill™’s Y Axis
15mm Rails
Motor Mounted Here
Details TBD
Floating Pillow Block
Ball Nut
Optional Linear
Position Encoder
Fixed Pillow Block
12x5 Ball Screw
Property of Roger Cortesi, MIT Precision Engineering Research Group. DO NOT COPY or TRANSMIT without written permission.
The New X and Y Carriages
Obviously the X and Y Carriage from the Modified MiniMill™ wouldn’t
work so here are the new ones
Z Trucks (4)
Y Ball Nut
Mounting Point for
Optional Linear Encoder
Z Ball Nut
X Trucks (4)
Y Trucks (4)
X Carriage
Y Carriage
Property of Roger Cortesi, MIT Precision Engineering Research Group. DO NOT COPY or TRANSMIT without written permission.