| Main methods for machining eccentric shaft | 1. Generally, the four jaw chuck is used for clamping eccentric
workpieces with small quantity and low precision. When turning the
eccentric workpiece on the four jaw chuck, first draw a line on the
workpiece. It is to draw an eccentric circle and ensure the
horizontal and vertical cross lines. So as to determine its
position in the four jaw chuck according to these lines. 2. When machining eccentric workpieces with small eccentricity (e ≤
5-6mm) and short length but large number of eccentric workpieces,
the three jaw self centering chuck can be used for machining. When
turning, the outer circle and length shall be turned first. Then it
is clamped on the three jaw chuck, and a gasket is placed on one
jaw to make the workpiece eccentric for turning. The thickness of
the pad can be calculated by the following formula. X=1.5e ×
(1-e/2d) (x=gasket thickness; e=eccentricity of the workpiece;
d=diameter of the clamped part of the three claws) During actual
turning, due to the deviation between the contact position of the
long claws and the workpiece, a correction constant shall be added
to the deformation after the clamping of the soil gasket. X
real=x+1.5 △ e (x real=actual gasket thickness; x=calculated
thickness; △ e=measured eccentricity error after test) 3. Turning eccentric workpiece on double chuck This method is to
clamp the three jaw self centering chuck on the four jaw single
acting chuck for alignment, and then move an eccentric distance for
clamping. In the future, you can turn eccentric workpiece by
clamping the workpiece on the three jaw self centering chuck. In
this way, it is unnecessary to align the workpiece. When moving the
position of the three jaw chuck, first clamp the optical shaft in
the three jaw self centering chuck, use the dial indicator to
determine the eccentricity, and finally determine the position of
the three jaw chuck in the four jaw chuck. 4. When turning the eccentric workpiece between two thimbles, the
eccentric workpiece with long length can be clamped between two
thimbles for turning, and the workpiece can be driven to rotate by
the chicken heart clamp. The center of both ends of the eccentric
workpiece processed between two thimbles, and the eccentric center
hole is generally processed on the boring machine, because it is
difficult to ensure the center of both ends on the machine, and the
direction of the eccentric center hole is consistent and parallel. 5. Eccentric chuck eccentric chuck eccentric distance adjustment is
convenient, versatility, high precision is a more ideal eccentric
tool. 6. In the special fixture, the eccentric workpiece can be turned on
the special fixture when the machining length is short, the
precision is high and the number of eccentric workpiece is very
large. 7. In the actual processing of eccentric workpieces with large
eccentricity and low precision requirements, another clamping
method is summarized, namely, three jaw boring plus gasket
clamping. That is, when the three jaw self centering upper jaw,
first install the first jaw, then gently move the collet, so that
the end screw of the collet rotates about one or two turns, and
then install the second and third jaws, so that the three jaws of
the collet naturally form eccentricity. Since the eccentricity is
not adjustable, shims should be added to adjust it. The advantage
of this method is simple, convenient and fast, but the disadvantage
is that the positioning accuracy is not high. |
