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[技术] 2轴微型数控车床

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发表于 2014-5-20 07:29:17 | 显示全部楼层 |阅读模式
2轴微型数控车床

CNC Micro Lathe

2轴微型数控车床

2轴微型数控车床

Taig Micro Lathe converted to CNC. Photo shows cutting first taper without a compound.
Since the CNC mill's computer, breakout board, stepper motor controller & MPG were already in-place,
it was very cost-effective to convert the Taig Micro Lathe to CNC by installing different lead screws,
designing brackets for the stepper motors & adding limit switches. The stepper motor
control panel was easily redesigned & rewired to provide switchable X & Z axes outputs.

2轴微型数控车床

2轴微型数控车床

Back to baseline lathe configuration. Mounted on a ?" aluminum plate.
 楼主| 发表于 2014-5-20 07:30:28 | 显示全部楼层
X-axis Lead Screw

2轴微型数控车床

2轴微型数控车床

Three, 6-32 screws hold the motor mounting plate. The stepper is held on with four, 10-32 cap-head bolts.
The motor has a 1.5" diameter lip that fits into & centers on the NEMA 23 dimensioned motor bracket hole.

2轴微型数控车床

2轴微型数控车床

Initial bracket design using ?" aluminum plate. A transfer punch aided alignment.
 楼主| 发表于 2014-5-20 07:30:58 | 显示全部楼层

2轴微型数控车床

2轴微型数控车床

Exploded view of the zero-backlash spline-shaft coupler with fabricated ?-20 LH lead screw adapter.

2轴微型数控车床

2轴微型数控车床

Zero-backlash shaft coupler assembled. A second, simpler adapter was also made.
 楼主| 发表于 2014-5-20 07:33:39 | 显示全部楼层

2轴微型数控车床

2轴微型数控车床

The main bracket is held underneath the carriage by OEM bolts that guide the brass gib. The original 4-40 threads were enlarged to 8-32 for increased strength. Do not over clamp these bolts as it will affect the gib.

2轴微型数控车床

2轴微型数控车床

Changed the coupler to use a simple shaft size adapter (cylinder) with a hole for the setscrew to past through.
Note the flats on the lead screw so a 3/16" open-ended wrench can be used to hold it from turning when tightening/loosening the lock nut on the other end where the bronze radial/thrust bearings are located.
Since the stepper motors do not have thrust bearings, it is best to isolate them from those forces.
Along the lead-screw axis the plastic coupler has a small 1mm gap so it is impossible to transfer thrust forces though this is quite unlikely as the the front thrust bearing has all but eliminated any movement.
The same precaution is taken for the Z-axis lead screw coupler, too.
 楼主| 发表于 2014-5-20 07:34:03 | 显示全部楼层

2轴微型数控车床

2轴微型数控车床

Radial & thrust bearings are made out of oil-impregnated, sintered bronze. It threads into the original location.
The lead screw was made of ?-20 SS LH threaded rod. OEM geometry was replicated but to tighter tolerances.
Note, oil-impregnated bronze is soft.

2轴微型数控车床

2轴微型数控车床

A nylon acorn nut covers the sharp threads.
 楼主| 发表于 2014-5-20 07:34:41 | 显示全部楼层

2轴微型数控车床

2轴微型数控车床

Anti-backlash, left-hand, brass jam nut is held in place by a 8-32 pointed setscrew on top of the slide.
The lead screw nut channel bottom on the carriage, was relieved using a ?" ball-nose end mill.

2轴微型数控车床

2轴微型数控车床

Added a spring to further reduce backlash. The adjustable left bracket uses a T-nut, washer, nut & 10-32 bolt.
The spring does not affect the bracket geometry.
 楼主| 发表于 2014-5-20 07:35:32 | 显示全部楼层

2轴微型数控车床

2轴微型数控车床

Added a second inner spring.

2轴微型数控车床

2轴微型数控车床

Added an upper stiffening bracket for the X-axis stepper motor. The left edge is chamfered to clear the cam.
The part bolts to the carriage & the limit switch housing. It has two notches that engage the mating parts' edges.
 楼主| 发表于 2014-5-20 07:36:01 | 显示全部楼层

2轴微型数控车床

2轴微型数控车床

The two right bolts had to clear the cam channel located just above. They screw into tapped blind holes.

2轴微型数控车床

2轴微型数控车床

Another view of the engaged bracket notch.
 楼主| 发表于 2014-5-20 07:37:04 | 显示全部楼层
Z-axis Lead Screw

2轴微型数控车床

2轴微型数控车床

Precision reaming a ?" hole in a block to accept the two, oil-impregnated bronze lead-screw nuts.

2轴微型数控车床

2轴微型数控车床

Bronze oil-impregnated bearing material threaded for the ?-20 RH precision lead screw.
 楼主| 发表于 2014-5-20 07:37:34 | 显示全部楼层

2轴微型数控车床

2轴微型数控车床

Outside diameter of the lead screw nuts machined to 0.750" & cut apart.
Extra material was left to make the hex nut for wrench adjustments.

2轴微型数控车床

2轴微型数控车床

Exploded view of the lead screw nut housing as well as the bottom of the motor bracket screws.
Note the square groove in the lead-screw nuts & the half-dog point setscrews that engage them.
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