SI21522A - Clamping assembly of apparatus for determination of wear resistance due to sliding friction - Google Patents

Abstract

The purpose of the invention is to ensure a suitable clamping assembly for an apparatus for determination of wear resistance due to sliding friction, which will enable the levelling of an already inserted rotating test piece (3) into a holder (1) immediately before its final fixing, and at the same time the clamping and unclamping of a test piece (3) without any need of removal of this holder (1) from the apparatus. The holder (1) comprises at least essentially a flat bottom (120), in the central area (121) of which a spring-supported ball (125) is installed, supporting a levelling plate (2) with a test piece (3) fixed onto the latter. The measuring surface (31) of a test piece (3) is facing away from the said levelling plate (2). The connection between the holder (1) and the levelling plate (2) with a test piece (3) fixed onto the latter is achieved by threaded holes (13', 13", 13'") available on the bottom (120) of the holder and distributed symmetrically to the rotational axis (110) and by bolts (23', 23", 23'") insertable under appropriate slackness through respective holes (22', 22", 22'") within the levelling plate (2).

Description

Clamping assembly for sliding friction wear tester

The invention can be classified in the field of physical testing and measurement and characterization of materials, namely the determination of wear resistance due to sliding friction.

The invention is based on the problem of providing a suitable clamping assembly for a device for determining the resistance to wear due to sliding friction, which will allow leveling in the holder of a rotating tester already mounted just before its final clamping, and at the same time clamping and extending the test piece without the need for removing this holder from the device.

A well-established and recognized method of measuring the resistance to wear due to sliding friction dictates that the wear resulting from sliding friction be measured on one of the surfaces of a flat rotary test piece rotating about an axis perpendicular to said measuring plane, at the same time however, a stationary tester is pressed against said measuring surface with a certain force, whose direction and strength are predetermined.

Measurements can be made on a device, such as e.g. known as PIN-DISC. Such a device comprises a frame in which, by means of a vertical mandrel, a holder is formed, which is designed as a hollow cylinder or. like a kind of cylindrical, flat-bottomed cup. A support plate can be attached to this holder in the area of its bottom, eg. glued rotary test piece. By means of said mandrel, which is connected to a suitable propellant by means of suitable transmission means, the holder is rotatable about a horizontal axis, the test plane being horizontal. The test subject is usually designed as a disc. On the other hand, there is provided in the frame of the device in question a bed in which a stationary tester is engaged, the device allowing this stationary tester to exert a predetermined force against the measuring surface of the rotating tester with a predetermined force on a given radius relative to the axis rotation of the rotating test piece.

Basically, these features of the said device are also covered by US 6,418,776 BI, which in addition describes a number of other details concerning a completely different problem from that of the present invention. Namely, the solution of US 6,418,776 BI is based on the criticism of a previously known device according to US 5,795,990, in which both subjects are rotatable, creating an orbital, planetary motion between them, whose effects are difficult to measure and therefore the results are often unclear or unclear. inaccurate. Due to the presence of two actuators, it would also result in considerable deformation in the device itself, which again leads to a less accurate measurement. Therefore, the purpose of US 6,418,776 BI is to remedy the aforementioned deficiencies and, in addition, to expand the measurement capabilities in other ways. For the purposes of evaluating the present invention, it is sufficient to conclude that US 6,418,776 BI is leveled by lowering or lowering. it does not even deal with the stationary subject. The tester is simply screwed to the bottom of the holder, and with a cane, is held in place by the device. However, it should be appreciated by the skilled person that in this way satisfactory measurement results can only be expected if the measuring surface is indeed flat and its perpendicularity to the axis of rotation is at the same time ensured. Just by screwing the test piece into the bottom of the holder, this simply cannot be achieved. However, it is possible to achieve this, for example. in this way, to remove the retainer, a test piece with a precisely machined flat measuring surface is placed therein, and then, together with the retainer, the holder is clamped to another leveling device. When, with proper leveling and checking of deviations e.g. by means of a measuring clock, they reach the perpendicularity of the measuring surface with respect to the axis of the mandrel, they can clamp tm together with the holder and the test piece placed in the holder back into the measuring device. In this case, a sufficient number of holders should be available to ensure adequate measurement concentration and utilization of the measuring device, since only one can be attached to the device during the measurement of wear resistance, while the remaining test pieces can be leveled by the remaining holders. Another way of ensuring rectangularity! between the measuring plane of the rotating specimen and the axis of rotation can be ensured by extremely precise machining of the two parallel surfaces of the rotating specimen, as well as the extremely carefully designed holder, with extreme care during mounting of the specimen in the holder. Given the costs involved, such an approach seems particularly dubious.

The present invention relates to a clamping assembly of a device for determining wear resistance due to sliding friction. Such assembly shall consist of at least a holder and a rotary test piece. Said holder comprises a tm, by means of which it can be clamped into the device, thereby ensuring the positioning and rotation of the holder about its axis. The rotary test piece is attached to said holder in such a way that its measuring surface runs perpendicular to said axis of the holder. According to the invention, the holder comprises at least a substantially flat support surface, in particular the bottom of the recess, which extends at least substantially orthogonal to the rotary axis and in which a spherically supported ball is supported by a pivot-supported ball supported by said axis. with a test piece attached to it, the measuring surface facing away from said leveling plate. In this case, the leveling plate and the holder are provided with at least three connecting means, each of which, optionally, allows locally moving the leveling plate in the direction towards the supporting surface of the holder and against the force of the spring-supported spheres, or. moving this leveling plate away from the support surface of the holder. Further, a holder is provided in the central area of the support surface, namely the bottom, with a recess extending in the axial direction and in which a spring is supported, with a partially extending ball supported from said recess. Preferably, a slide is inserted between the spring and the ball, particularly the taxon, so that its front facing surface is straight and perpendicular to the rotary axis. The aforementioned a connecting means between the holder and the leveling plate with the test piece attached to it are preferably formed with respect to the rotary axis of the symmetrically arranged threaded holes available in the bottom of the holder and the screws that can be inserted through the corresponding holes in the leveling plate with a suitable slack.

The invention will now be explained on the basis of the exemplary embodiment shown in the accompanying drawing, where FIG. 1 shows the clamping assembly of a device for determining the wear resistance due to sliding friction, together with a rotating test piece and in the plan, FIG. 2 is a cross-sectional view of a cross-sectional view of the horizontal plane II - II of FIG. 1.

The clamping assembly consists of a holder 1 in which the leveling plate 2 is mounted with a rotating test piece 3. The axisymmetrically designed holder 1 consists of a mandrel 11 and a cylindrical recess 12 with a straight and with respect to the longitudinal axis 110 of the holder 1 with a rectangular bottom 120. The mandrel 11 is constructed in such a way that it can be clamped into the corresponding (not shown) socket of each measuring device, thereby providing positioning of the holder 1 on the one hand, and on the other, providing a drive for ensuring the rotation of the holder 1, and thus also of the rotary subject 3.

In the bottom 120 of the holder 1 there are three threaded holes 13 ', 13, 13' symmetrically arranged in the axis 110. In the central region 121 of the bottom 120 of the holder 1, a recess 122 is provided in which a spring-supported ball 125 is mounted, which in the case shown is mounted via a spring 123 located in said recess and through a slider 124 located in said recess 122 and is supported by said spring 123. The slide 124 is designed with a flat face 1240 that faces the ball 125 or. away from the spring 123 to achieve a correct alignment of the spring-supported ball 125.

Test subject 3 as such is machined to a certain extent such that at least its measuring surface 31 is flat, which means that at least the flatness of said surface 31 is achieved within the frame for the purpose of carrying out measurements of tolerances.

The test surface 3 is fixed to the leveling plate 2 in the most expedient manner by gluing it to the available surface 21 of the leveling plate 2, so that the contact surface 32 of the tester 3 faces the leveling plate 2 and its measuring surface 31 away from that plate 2.

The leveling plate 2 is provided with three through holes 22 ', 22, 22', the arrangement of which is aligned with the arrangement of the previously mentioned threaded holes 13 ', 13, 13' in the bottom 120 of the holder 1. Through said holes 22 ', 22, 22' are insertable screws 23 ', 23, 23' which pass through the leveling plate 2 with adequate looseness and can be screwed into the holes 13 ', 13, 13' in the bottom 120 of the holder 1. There is a central arrangement provided on the underside of the leveling plate 2. center the nest 24, which is intended to fit the ball 125 and is conical in the example shown, but generally can be spherical or otherwise made.

Which test piece 3 is mounted on the leveling plate 2 and which the spring-supported ball 125 is mounted in the recess 122 so that it protrudes partly from the area of said recess 122 above the bottom plane 12 of the holder 1, so that the test plate 3 is turned away from mandrel 11, upwards as appropriate. The leveling plate 2, with its nest 24, fits into the ball 125 and, thanks to the projection of the ball 125 from said recess 122 on the surface of the bottom 120 of the holder 1, rests at a single point, while the rest of the plate is kept at a distance from the bottom 120 of the holder 1. Thereafter through holes 22 ', 22, 22' in panel 2, insert the screws 23 ', 23', 23 'and screw them to the holes 13', 13, 13 '' in the bottom 120 of the holder 1. To this extent, the level plate 2 is pivoted to ball 125, which is supported by a spring 123, thereby squeezing the plate 2 away from the bottom 120 of the recess 12 of the holder 1. On the other hand, the leveling plate 2 in each area selected can be approached to the bottom 120 or away from the bottom 120 by tightening or loosening the screws 23 ', 23, 23'. In this way, it is possible to achieve the leveling of the plate 2 and thus also the measuring surfaces 31 of the subject relative to the plane of the bottom 120 or. with respect to the longitudinal axis 110 of the holder or. thorn 11. If e.g. to the position as in FIG. 2 is a pure schematically illustrated stationary test piece 4, instead of clamping an unspecified measuring clock, the sensor of the latter is located on the measuring surface 31 of test specimen 3. By slowly rotating the holder 1 and successively tightening or loosening the three spaced screws 23 ', 23, 23'. thanks to the support of the plate 2 with the ball 125, the perpendicularity of the measuring surface 31 of the test specimen 3 can be achieved practically independently of the geometry of the bottom 120 of the holder or the contact surface 32 of the specimen and, in particular, without any clearance.

When said leveling of the test piece 3 is completed and therefore the measuring surface 31 of the rotating test piece 3 is perpendicular to the axis of rotation 110, it is possible to rotate the test piece 3 at a suitable speed, and then against the measuring surface 31 with the required force, e.g. 100 N, press stationary test piece 4, which in FIG. 2 - as already mentioned - merely schematically illustrated. After a certain time of testing, by removing the holder 1 and loosening the screws 23 ', 23, 23', the leveling plate 2 is removed from the holder 1, after which it is possible to observe the measuring surface 31 and to make appropriate measurements of the rotary tester 3 and, if necessary, the stationary tester 4.

It will be appreciated by those skilled in the art that measurement may also be performed if a layer of lubricant is provided between test pieces 3, 4. The leveling of the rotary test piece 3 is also possible if the lubricant is coated or if the lubricant is located at the bottom 120 in the recess 12 of the holder 1, practically without complications in exactly the same manner as previously described.

Claims (8)

PATENT APPLICATIONS A clamping assembly for a sliding friction wear test device comprising at least a holder (1) and a rotary test piece (3), said holder having a mandrel (11) by means of which it can be clamped into the device and thereby to provide positioning and rotation of the holder (1) about its axis (110), and wherein the rotating test piece (3) is fixed on said holder (1) in such a way that its measuring surface (31) runs perpendicular to said axis (110) ) of the holder (1), characterized in that the holder (1) comprises at least substantially flat support surface, in particular the bottom (120) of the recess (12) extending at least substantially orthogonal to the rotary axis (110), in which the central an area (121) which coincides with said axis (110) is provided with a spring-supported ball (125), which is supported by a leveling plate (2) with a test piece attached to it (3), whose measuring surface (31) is turned away from said leveling plate (2), wherein the leveling the plate (2) and the holder (1) are provided with at least three connecting means (13 ', 13, 13'; 22 ', 22, 22'; 23 ', 23, 23'), which each optionally allow for the local movement of the leveling plate (2) towards the support surface (120) of the holder (1) and against the force of the spring-supported balls (125) or. moving this leveling plate (2) away from the support surface (120) of the holder (1). Clamping assembly according to claim 1, characterized in that the holder (1) is provided in the central region (121) of the support surface, namely the bottom (120), with a recess (122) extending in the axial direction and in which it is inserted a spring (123) supporting a partially extending ball (125) from said recess (122). Clamping assembly according to claim 2, characterized in that a slide (124) is inserted between the spring (123) and the ball (125). Clamping assembly according to claim 3, characterized in that a slider (124) is inserted between the spring (123) and the ball (125), whose face (1240) facing the ball (125) is straight and perpendicular to the rotary axis (110). Clamping assembly according to any one of the preceding claims, characterized in that the connecting means (13 ', 13, 13' '; 22', 22, 22 '; 23', 23, 23 ') between the holder (1) and the leveling the plate (2) with the test piece attached to it (3) is formed by symmetrically arranged threaded holes (13 ', 13, 13'), which are available in the bottom (120) of the holder (1) and the screws (1) with respect to the rotary axis (110). 23 ', 23, 23') which can be inserted through the corresponding holes (22 ', 22, 22') in the leveling plate (2) with a suitable slack. Clamping assembly according to any one of the preceding claims, characterized in that the leveling plate (2) is provided with a centered socket (24) on its side facing side in the central area in order to receive the ball (125). . Clamping assembly according to claim 6, characterized in that the price of the trimmer socket (24) is at least substantially conical. Clamping assembly according to claim 6, characterized in that the centering socket (24) is at least substantially spherical.