Wear measuring arrangement for bearings

In a wear measuring arrangement for bearings, a support sleeve is slidably mounted in one of the bearing rings, and supports an inductive sensor having a plunger type armature with a probe tip. The support sleeve is mounted to be held in a position with the probe tip away from the other bearing part, and to be released by a control shaft. Upon release, a spring arranged in the bore of the support sleeve resiliently urges the probe tip to engage the other bearing part and pierce any grease layer on the surface thereof.

This invention relates to a wear measuring arrangement for bearings, 
particularly large rod end bearings for steel converters, in which a probe 
tip engages a sliding surface of a bearing part in a measuring position, 
and is lifted from the sliding surface after measurement by an adjusting 
arrangement connected to the sensing probe. 
A wear measuring arrangement of the above type is known. The known 
measuring arrangement consists of a proportionally large housing, in which 
a sensing probe is slidably guided, and is positioned against a shaft by 
air pressure. This arrangement has a large overall height, and requires a 
special air pressure supply and a special control element. 
It is also known to provide a contactless sensor, in the overlying parts of 
a bearing housing, which serves to provide a continuous measurement of 
bearing changes of the bearing pin upon wear of the sliding layer. This 
known wear measuring arrangement has the disadvantage that fault 
measurements can arise as a result of the grease layer or the like formed 
on the sliding surface. 
It is therefore the object of this invention to provide a wear measuring 
arrangement of the above type which only requires a minimum volume and can 
be arranged in a bore of a bearing part. 
It is a further object to provide a wear measuring arrangement wherein the 
probe tip is so urges against the measuring surface that a grease layer or 
the like on the bearing part is pierced and the accuracy of the 
measurement is not adversely affected by the grease layer. 
These objects are achieved in accordance with the invention by providing a 
slidable support housing with a preferably inductive sensor inserted 
either in a bore on the bearing part or in the bore of a sleeve connected 
to the bearing part. 
The wear measuring arrangement in accordance with the invention provides a 
high measuring accuracy, so that the degree of wear of the sliding 
material may be determined at any time. 
According to an advantageous further embodiment of the invention, the 
armature of the inductive sensor is connected to a guide shell arranged in 
the bore of the support sleeve. A spring abuts the sides of the guide 
shell facing away from the surface to be measured in the upper position of 
the support sleeve the other side of the guide shell engaging a spring 
ring or the like arranged in the bore of the support sleeve, with 
prestress. As a result the plunging-type armature is firmly guided for a 
larger measuring displacement and the probe tip is resiliently forced 
against the sliding surface before the support sleeve has reached a lower 
position.

FIG. 1 illustrates a large rod end bearing having an outer ring 1, an inner 
ring 2, and sliding elements 3 between the bearing rings, the sliding 
elements 3 being arranged with a cage 4 connected to the outer ring 1. The 
wear measuring arrangement 5 illustrated in FIGS. 2 and 3 is located in a 
radially extending bore 6 of the outer ring 1, and consists of an 
inductive sensor 7 which measures radial displacement of the inner bearing 
ring 2 with respect to the outer bearing ring 1. The measurement value can 
be read from an indicator (not shown) located outside of the bearing and 
connected to the sensor 7 by a cable 8. In order to ensure that the probe 
tip 9 of the inductive sensor 7 does not constantly rub against the 
sliding or measuring surface 10 of the inner ring in operation, it is 
raised by a control shaft 11 which is guided in a bearing 13 provided in 
an axially extending bore 12 of the outer ring 1. The control shaft 11 is 
provided with a square end 14 so that it can be operated externally during 
operation, so that the probe tip 9 can be brought at any time to the 
measuring position. 
The inductive sensor 7 illustrated in enlarged view in FIG. 2 has a coil 15 
and a plunger-type armature 16 and is held in the bore 18 of a support 
sleeve 19 by spring rings 17. A guide shell 20 having a U shaped 
cross-section is moveably positioned in the bore 21 of the support sleeve 
19 and is connected to the armature 16 by nuts 22, which are threaded on 
the armature and engage opposite sides of the guide shell. A helical 
spring 23 abuts the free end of the guide shell 20, the other end of the 
spring 23 being supported on a shoulder 24 of the support sleeve 19. The 
support sleeve 19 is slidably positioned in the bore 25 of a sleeve 26 
connected to the outer ring 1. The maximum measurement range of the 
inductive sensor 7 can be adjusted by turning the nuts 22. 
When measurements are not being taken, the support sleeve 19 is held in its 
upper position by means of a ball 27 which engages a recess 28 in the 
outer surface of the support shell 19. At the same time the guide sleeve 
20 abuts the spring ring 29 in the lower end of the support body 19, under 
the pressure of the compressed spring 23. In this position the probe tip 9 
does not contact the sliding surface 10 of the inner ring 2. In order to 
measure the wear, the support sleeve 19 is released from the withdrawn 
position by means of a cam 30 on the control shaft 11, which engages a 
recess 31 of the support sleeve 19, so that the ball 27 is urged into its 
bore 33 in the sleeve 26, against the pressure of the spring 32. The 
support sleeve 19 has an upper flange 34 adapted to engage a shoulder 35 
in the inner bore of the outer sleeve 26 in its lower position, so that 
the probe tip 9 of the plunging armature 16 is pressed rigidly against the 
sliding surface 10 of the inner ring 2. At the same time the guide shell 
29 is lifted about a distance X from the facing surface of the spring ring 
29. Each radial displacement of the inner ring 2 results in a 
corresponding change in the distance X, which can then be derived from the 
indicating apparatus and is a measure of the bearing wear. Since the probe 
tip 9 of the plunging armature 16 is pressed against the sliding surface 
10 by the spring 23, it will eventually pierce the hardened grease layer 
or the like formed on the sliding surface 10 so that the accuracy of the 
wear measurement is not adversely affected. 
The above-described arrangement constitutes only one embodiment of the 
invention. It is apparent that changes may be made within the scope of the 
invention. For example, the support sleeve may be provided with a toothed 
profile on one side, engaged by a pinion on the control shaft. In 
addition, the wear measuring arrangement in accordance with the invention 
can be employed for thrust bearings, as well as the disclosed arrangement 
for measuring wear of radial bearings.