WO2017202396A1

WO2017202396A1 - Jig for mounting samples in a test device for material contact fatigue tests

Info

Publication number: WO2017202396A1
Application number: PCT/CZ2016/000105
Authority: WO
Inventors: Eva SCHMIDOVÁ; Bohumil Culek; Jiři TLUSTOŠ
Original assignee: Univerzita Pardubice
Priority date: 2016-05-26
Filing date: 2016-09-15
Publication date: 2017-11-30
Also published as: EP3465137A4; CZ307036B6; EP3465137A1; EP3465137B1; CZ2016312A3

Abstract

The jig (1) for mounting test samples (8) in a testing device for material contact fatigue tests equipped with at least a rolling drum (3) and a testing set (4), which contains both a drive unit (41) whose entry shaft (411) for coupling with the bearing shaft (5) of the jig (1) is mounted coaxially with the rotating axis of the rolling drum (3), and the pressure unit (42) which is mounted displaceably in the direction perpendicular to the rotating axis of the rolling drum (3). The essence of the invention is that the jig consists of a bearing ring (101) and a pressure ring (102), which consist of flat circular discs of the same diameter adapted to ensure mutual concentric placement and clamping in the direction of the axis of the bearing shaft (5), where the bearing (101) and the pressure ring (102) are equipped with a set of at least two circumferentially spaced and mirrored semi-circular beds (103), which create an upwardly open cylindrical cavity (104) for inserting test samples (8) into on completion.

Description

Jig for mounting samples in a test device for material contact fatigue tests

Field of the invention

The invention comes under the area of the development of test devices for material contact fatigue tests and concerns the construction of jigs for mounting the tested material samples.

Background of the invention

Currently a range of special test devices exist for simulating the contact fatigue process in the loading of train wheel-rails, which vary in the measuring of the test sample due to the actual dimensions of the contact pair and the possibilities of achieving real loading parameters in operation. Along with the requirement to approach actual operating conditions when testing materials, a need also arises to test different materials under totally identical loading conditions. This requirement is not completely upheld anywhere with the current state of testing device technology.

From a study of patent literature it is found that all of the current testing device structures in this field work on the assumption that a material sample in the form of a disc is tested during individual rolling for given fixed conditions. After the completion of the test this material sample is removed from the device and replaced with another sample, which is then tested under the same conditions, if possible, for comparison purposes. This is how all known devices are conceived in principle as, for example, in the solutions given in the US4570348A, JPH10151903A, CN102384879A, KR20120000608A, PL219362B1 , CZ20040112A files. The basic disadvantage of the listed solutions and their application is that they do not allow for the comparison of different materials under absolute conditions because in every case of sample change, that is to a disc of a given material, inaccuracies occur when setting the test parameters, particularly geometric uncertainties when setting the contact positions, uncertainties in setting the loading forces in contact, uncertainty in setting the slide of the rolling parts, thus the driving wheel and the test disc. This all results in imprecise comparison of the results of individual material samples, and thus the determination of the most advantageous variants of the tested materials is also problematic.

When carrying out tests on material contact fatigue resistance a requirement is also made that material from the surface layers of the pair is also tested. The surface layers have differing mechanical characteristics after specific heat processing, which totally limits their contact fatigue resistance. The current test devices in accordance with existing patents do not allow the performance of material testing to a quality which realistically corresponds to the state of the materials in contact between the rolling elements, for instance the wheel-rail set.

The role of the presented invention is to introduce a new jig structure to fix samples in a testing device used for material contact fatigue tests, which allows the performance of exact comparison tests on several types of material, or the surface treatments of these materials, is structurally simple, and the dimensions of the used samples allow for material samples to be taken from the completed products, for instance train wheels, in layers which are decisive from the point of view of the lifespan and safety of train wheels and rails.

Summary of the invention

The defined objective is achieved by the invention which is a jig for mounting test samples in testing devices for material contact fatigue tests, equipped at least with a rolling drum and test set which contains both a drive unit whose entry shaft for coupling with a load bearing shaft is mounted on the co-axial with the rotating axis of the rolling drum, and also a pressure element which is adjustably mounted in a direction perpendicular to the rotation axis of the rolling drum. The invention is characterized in that the jig is made up of a load bearing ring and a pressure ring, which consist of flat circular discs of the same diameter and are adapted to ensure mutual concentric placement for clamping in the longitudinal axis of the bearing shaft, wherein the bearing ring and pressure ring are provided with a set of at least two circumferentially equally spaced and mirrored half ring beds which create the above mentioned open drum cavities for the insertion of the test samples.

In a preferred embodiment, the bearing ring for ensuring mutual concentrated placement with the pressure ring provided with a central recess, the loading ring and the pressure ring are axially clamped by a screw connection using clamping bolts placed in connecting holes which are created in the loading ring and pressure ring between mutually opposite beds, wherein on the bottom of the beds of the bearing ring clear radial assembly holes are formed.

In the optimum case the bearing ring and the pressure ring are supplied with a set of eight half ring beds.

The new invention achieves a greater effect in that the structural solution of the jig allows loading the material samples with a defined contact pressure on the surface. After placing the jig in the testing device it allows the testing of the material contact fatigue resistance when simulating operating conditions, where it is also possible to carry out continual evaluation of the material state at chosen stages of loading. The greatest advantage, however, is that the structure of the jig ensures the conduction of accurate comparative tests on several alternate materials under absolutely identical conditions. Brief description of the drawings

Concrete examples of the form of the invention are indicated schematically on the attached drawings, where

Figure 1 is an axonometric view of the testing device with the jig installed,

Figure 1 a) is a detailed view of area A of the jig contact with the inserted test material samples and the drum of the testing device from Figure 1 ,

Figure 2 is a side view of the test device from Figure 1

Figure 3 is an axonometric view of the jig with an example of its placement on the bearing shaft equipped with bearings.

Figure 4 is an elevation view of the jig placed on the bearing shaft in Figure 3,

Figure 5 is an axial longitudinal section of the jig set from Figure 4

Figure 6 is an axonometric view of the basic version of the jig with eight beds for the placement of test samples,

Figure 6a) is a view of the jig disc from Figure 6 after its disassembly,

Figure 7 is a view of the alternative version of the disc with two beds for the placement of testing samples,

Figure 8 is a view of an alternative version of the disc with six beds for the placement of test samples,

Figure 9 is an axonometric view of the adjustable clamping sleeve of the jig for its placement on the load bearing shaft, and

Figure 9a) is a longitudinal section of the adjustable clamping sleeve from Figure

9.

The drawings which illustrate the presented invention and concrete uses described in the following examples in no way limit the extent of the protection specified in the definition, but only illustrate the nature of the invention. Detailed description of the invention

The jig 1 is intended for installation on the test device for implementation of material contact fatigue tests, which is formed by a bearing base 2 created with the advantage of the form of welded profiled materials onto which the rolling drum 3 and test set 4 are mounted, which contains both a drive unit 41, whose entry shaft 411 is mounted coaxially with the rotating axis of the rolling drum 3, and also the pressure unit 42, which is mounted displaceably in a direction perpendicular to the rotating axis of the rolling drum 3. A special jig 1 is mounted on the load bearing shaft 5 to the entry shaft 41 1 of the driving unit 41 fitted with two bearings 6, whose position on bearing shaft 5 is limited by the adjustable clamping sleeve 7 equipped with support washers 7J_ and fixing nuts 72. The design of the adjustable clamping sleeve 7 is clear from Figure 9 and Figure 9a). On the end element of the bearing shaft 5 adjacent to the coupling with the entry shaft 411 of the driving unit 41. the test sample 8 is inserted in the demountable jig 1, whose position in light of the adjacent bearing 6 is limited by a spacer insert 10, whose fixation on the bearing shaft 5 is achieved using an end clamping sleeve 9 equipped with a safety washer 9J_ and tightening nut 92.

The actual jig 1 consists of a basic structure illustrated in Figure 6 and Figure 6a) made from a bearing ring 101 and a pressure ring 102, which consist of flat circular discs of the same diameter where the bearing ring 101 is given a central insert to ensure mutual concentric placement 1011. Both rings IPJ_. and 102 are equipped with a set of eight half ring beds 103 for inserting test samples 8. The beds 103 are evenly positioned along the circumference of both rings 101 and 102 mirrored opposite each other and are directed radially from the outer perimeter towards the centre of the jig 1. With this bed structure 103 the completion of the jig 1 creates an upwardly open cylindrical cavity 104 for the insertion of test samples 8, as is evident in Figure 6. The bearing ring 10J. and the pressure ring 102 are clamped with a bolted connection by means of tightening bolts 105 with a recessed head inserted in connecting holes 106, which are created in both rings 101 , 102 between the mutually adjacent beds 103. And finally clear radial holes 107 for assembly are formed in the bottom of the beds 103 of the bearing ring 101, which allow easier removal or pressing out of the test samples 8 from the beds 103 after completion of the tests.

When carrying out tests with test samples 8 from various materials, they are placed in the cavities 104 of the beds 103 created by both rings 101 , 102 which are then clamped with the help of tightening bolts 105. The jig 1 along with the inserted samples 8 are subsequently placed in the test device, which, with its rolling drum 3, creates a contacting rolling pair with the perimeter element of the jig 1. After setting the required load parameters to simulate a real load, e.g. the contact between a wheel and a rail, with the help of a pressure unit 42, the power unit 41 is turned on and the testing of various materials is carried out under perfectly identical operating conditions. After completing the test the jig 1 is taken out of the device, the test samples 8 are pressed out of the cavities 104, are replaced by others, and the process can be repeated with any changes to the loading parameters.

The design of the described jig 1 is not the only possible structural solution of the invention, but as is evident in Figure 7 and Figure 8, it is possible to create a differing number of beds 103 on the perimeters of the rings 101. 102, for instance two, three, four, six or ten. Without affecting the essence of the invention, the jig l_can be mounted on the bearing shaft 5 not by means of the set comprising a fastening end sleeve 9 equipped with a safety washer 91 and a tightening nut 92 as illustrated in Figure 9 and Figure 9a), but, for example, with the aid of a grooved shaft or tongue and groove connection. The mutual centring of both rings can be achieved not only with the help of a centred fitting 1011 of the bearing ring 101 , but also, for example, additionally by a set of axially guided pins. Industrial applications

The jig 1 for testing material contact fatigue resistance is useful for comparative testing on multiple test samples 8 of the materials used when manufacturing, for example, train wheels and rails. All test samples 8 are tested under absolutely identical conditions so that the results of the contact fatigue tests clearly ranks the resistance of the individual material test samples 8. This is, from the perspective of industrial use, very important information for the manufacturer of, for example, train wheels or rails which have an impact in deciding on which material to use for manufacture, or what operational deployment is used.

Claims

1. The jig (1) for mounting test samples (8) in a testing device for material contact fatigue tests equipped- with at least a rolling drum (3) and a testing set (4), which includes both a drive unit (41 ) whose entry shaft (411 ) for coupling to the bearing shaft (5) of the jig (1 ) is mounted coaxially with the bearing shaft rotating axis of the rolling drum (3), and also a pressure unit (42) which is mounted displaceably in the direction perpendicular to the rotating axis of the rolling drum (3) are characterised by the fact that it is comprised of a bearing ring (101) and a pressure ring (102), which consist of flat circular discs of the same diameter and are adapted to ensure mutual concentric fitting and clamping in the direction of the bearing shaft (5), wherein the bearing ring (101) and pressure ring (102) are equipped with a set of at least two circumferentially and regularly spaced and mirrored half ring beds (103), which create, when completed, the entire jig (1) with an upwardly open cylindrical cavity (104) for inserting the test samples (8).

2. A jig (1) for mounting test samples (8) according to claim 1 is characterised by the fact that the bearing ring (101) is equipped with a centred fitting (1011 ) to ensure mutual concentric placement with the pressure ring (102).

3. The jig (1) for mounting test samples (8) according to claim 1 or 2 is characterised by the fact that the bearing ring (101) and pressure ring (102) are axially clamped by a bolted connection using a tightening bolt (105) mounted in the connecting holes (106) which are created in the bearing ring (101) and pressure ring (102) between the mutually adjacent beds (103).

4. The jig (1 ) for mounting test samples (8) in accordance with any of claims 1 to 3 is characterised by the fact that in the bottom of the beds (103) of the bearing ring (101) clear radial assembly holes (107) are formed.

5. The jig (1) for mounting test samples (8) in accordance with any of the claims 1 to 4 is characterised by the fact that the bearing ring (101) and the pressure ring (102) are equipped with a set of eight half ring beds (103).