Double flank rolling tester

Details Double flank rolling tester Double flank rolling tester

2002-08-12

2004-07-27

Lefkowitz, Edward (Department: 2855)

Measuring and testing

Simulating operating condition

Marine

Reexamination Certificate

active

06766684

ABSTRACT:

BACKGROUND OF THE INVENTION
The invention refers to an apparatus for testing gears by rolling without backlash with a mating gear according to the preamble of claim
1
. An apparatus of this kind is known from DE 34 15 631 C2.
Such apparatus are frequently used in automated gear production lines, for instance to test previously hobbed gear teeth before the next working step is performed on the same workpiece. This can prevent that a severely malformed gear is unnecessarily further processed or impedes the next working step, causes increased tool wear or even destroys the tool. Such a gear is discovered on time and removed from production as a result of the test.
For this purpose, each gear is automatically fed to a tester and is clamped on a motor-driven spindle having a stationary axis of rotation. A mating gear, or master gear, which loosely rotates on an oscillating slide, is advanced towards the test gear from a secure parking position and is automatically brought into mesh with the test gear. After the teeth of both gears got double flank contact, the oscillating slide is displaced somewhat against a spring force, so that an adequate test force exists at the so-called test center distance “a”. Then the spindle makes at least one full revolution with the test gear wherein the mating gear follows in tight mesh. Gearing deviations cause the oscillating slide to reciprocate in the direction of the center distance. These center distance variations are measured and, if a given upper or lower tolerance limit is passed, the tested gear is sorted out.
Obviously, such automatic testing apparatus are continuously further developed. The major selective criteria for this are high operational reliability, adaptability to different tooth systems, and test results containing as much information as possible. For example, numerous testers are already known that can be used for the described double flank rolling test. Here are only a few:
The double flank rolling tester according to DE 34 15 631 C2 has automatically operated engaging means characterized in that the loosely following mating gear is held in a specific rotary position by a magnet which is oriented toward a tooth of the mating gear, and that the work gear is assigned to a positioning device likewise working with a magnet or a sensor. This is to guarantee that for engaging, a tooth of the mating gear precisely matches with a tooth gap of the test gear. Aside from this, the tester as shown in
FIG. 6
of this published patent has the classic design, namely the movable first slide
14
is biased by a mechanical spring F and located on a second slide
16
which in turn is slidably mounted on a flat guide
18
of the base
2
in order to set the test center distance. The publication does not reveal whether a pneumatic cylinder or a stepping motor with threaded spindle is provided for this setting. The center distance deviations ±&Dgr;a are measured according to
FIG. 6
with a conventional electric probe.
The more recent utility model DE 200 05 299 U1 refers to an apparatus for quality testing of gears. In addition to a measuring unit that operates according to the single flank or double flank rolling principle and that has a master gear and a clamping device, this apparatus also has conveyor means for feeding the test pieces to the clamping device and for removing them after the rolling test. Its primary features are that the master gear and the test gears mounted on the clamping device rotate about vertical axes, and that the conveyor means has a gripper for grasping the test gears. Thus, the measuring unit hardly differs from the tester of DE 34 15 631 C2 described above, with two exceptions: According to
FIG. 6
of this publication, the oscillating slide
34
is not disposed on the slide
30
, but rather both slides are arranged one after the other on the base plate
28
; they are guided so as to be moved longitudinally in the same direction; and they are interconnected solely through spring means. This is intended to allow greater precision of the discoupled oscillating slide. Also, in this way the accelerations of the oscillating slide
34
during rolling of the gears are said to be more exactly measured by the sensor
38
than is generally the case if the center distance variations are measured with a linear encoder.
A further, known “testing machine, especially for gears” (DE 29 33 891 C2) deals with the accuracy and evaluation of measured signals from the center distance variations recorded by a sensor. This involves circuits for a now obsolete carrier frequency measuring amplifier. This publication is only significant for the prior art insofar as
FIG. 4
contains the schematic representation of a cardan-suspended probe to be used for measuring helix deviations and taper of the gear teeth. However, this probe is very complex in design and is not suitable for use in automated production lines.
The invention “Automatic Gear Checking Structure and Method” according to U.S. Pat. No. 4,488,359 is an improvement over the foregoing patent specification, since variations in the angle of rotation of the master gear relative to the test gear are to be measured in addition to the center distance variations, to enhance the validity of the measurement. To be sure, the circuits described here are somewhat more modern, but the mechanical design of the apparatus, which again is only schematically shown, has hardly been developed further. According to its
FIG. 3
, the master gear
40
is held in a fork
66
so as to rotate about its horizontal axis
98
. The fork
66
merges into a cylindrical shaft
68
which in turn is easily pivotable about the axis
96
and adapted to be easily displaceable in the same bearing in the longitudinal direction
90
. Inductive positional transducers
20
and
22
are to record the movements that may occur in the testing process. In this invention, however, no second slide or corresponding means is provided by which another test center distance could be set, for instance to test gears with larger diameters. Instead, there is a slide
44
which supports a rotatable spindle
51
and which can be reciprocated coaxially to the second spindle
58
by a working cylinder
48
. The test gears
38
, which have a center bore, are automatically centered and clamped by this means. For this purpose an inclined ramp
36
is provided, on which the test gears are fed by gravity to the testing apparatus. After testing the slide
44
moves back, the test gears are released and fall for further transport onto a second inclined ramp
42
.
A double flank rolling tester is known from DE 42 31 275 A1, in which a mounting device supporting a master gear or a test gear can be driven linearly relative to a device base by a motor and an acme threaded spindle.
Double flank rolling testers differ significantly from single flank rolling testers in which gears are tested at a fixed center distance. In the latter case only one flank of any tooth comes into contact when the two gears are rotated, and the instantaneous angle deviation of the driven gear is measured relative to the theoretically correct angular position resulting from the transmission ratio. For example, a device of this type is described in the U.S. Pat. No. 3,358,374.
In other types of measuring devices that are neither double flank nor single flank rolling testers there are developments utilizing linear motors, for instance to position a probe in X, Y, and Z directions. They replace the conventional combination of electric motor and ball screw, such as those frequently used in 3D measuring devices. A particularly precise, but very complex solution is described in DE 38 23 978 A1. In this linear guide means for precision machines the movable part is supported relative to the stationary part by magnetic or air bearings and the electrically driven linear motor is engineered to be superconducting, so that the heat losses in the magnet coils do not affect the accuracy of the measuring device. This can be necessary for absolute longitudinal measurements in coordinate m

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