GB1561733A

GB1561733A - Hardness testing machine

Info

Publication number: GB1561733A
Authority: GB
Original assignee: SIDAWAY J
Current assignee: SIDAWAY J
Priority date: 1975-09-19
Filing date: 1975-09-19
Publication date: 1980-02-27
Also published as: GB1506765A

Description

(54) HARDNESS TESTING MACHINE (71) I, JOSEPH TREVOR SID AWAY, a British Subject of 138, Leavale Road, Norton, Stourbridge, West Midlands DY8 2AB, do hereby declare the invention, for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a hardness testing machine of the kind (hereinafter called the kind specified) comprising a support for an object which is to be tested, an indenter which, in use, forms an indentation in the object, a mechanism for urging the indenter against the object under test and an optical system for measuring a dimension of the indentation after the indenter has been withdrawn therefrom.

Generally, in a hardness testing machine of the kind specified, the optical system comprises a travelling microscope adapted for use in measuring the diameter of the indentation.

A disadvantage of known hardness testing machines of the kind specified is that such machines cannot be used with the indenter mounted directly on an indenter spindle, to test the hardness of internal surfaces of workpieces. To enable the known machines to be used for such measurements, the machines are adapted by the interposition of a goose neck between the indenter spindle and the indenter. Generally, a range of different goose necks is provided with known machines of the kind specified to enable hardness measurements to be made on various surfaces of workpieces of various sizes and shapes. The use of goose necks in machines of the kind specified has a number of disadvantages. The assymetrical shape of a goose neck results in a greater deflection of the machine, when under load, than occurs when the indenter is mounted direct -ly on the spindle.When a goose neck is used, it is difficult to maintain proper alignment of the indenter with the indenter spindle. Large goose necks, which are necessarily heavy, require indenter spindles of special form to enable such goose necks to be properly secured to the spindle.

Particularly in the case of heavy goose necks, the mechanism for urging the indenter against the object under test must be adjusted to compensate for the weight of the goose neck which is applied to the indenter.

When such adjustments have been made, and the machine is to be used without a goose neck, special weights can be added to the mechanism to compensate for the absence of the goose neck, but this complicates use of the machine. It will also be appreciated that the provision of a variety of goose necks with each machine contributes significantly to the overall cost. Furthermore, the visibility of the surface area of the object at which the hardness is to be tested is restricted when a goose neck is used.

According to the present invention, there is provided a hardness testing machine of the kind specified wherein the indenter is mounted on a lever (called herein the indenter lever) and at least one element of the optical system is also mounted on said indenter lever.

Tests of the hardness of internal surfaces of objects and of other surfaces with poor accessibility can be made more conveniently with a machine in accordance with the invention than with known machines of the kind specified.

Preferably, the indenter lever has a fulcrum adjacent to one of its ends and the indenter and said element of the optical system are mounted on the lever adjacent to its opposite end.

The indenter and said element may be mounted on a turret which forms a part of the indenter lever and which can rotate relative to a further part of the lever about a longitudinal axis of the lever.

The invention will now be described, by way of example, with reference to the accompanying drawings wherein: Figure 1 is a diagrammatic illustration of a known hardness testing machine incorporating an indenter spindle.

Figure 2 shows a cross section of a novel machine having an indicator for indicating the depth of an indentation made in an object under test, Figure 3 shows an elevation of a front end of the machine of Figure 2, Figure 4 shows an end view of an indenter lever of a modified form of the machine shown in Figure 2, and Figure 5 shows a part of a cross section of the lever of Figure 4.

The known machine illustrated in Figure 1 comprises a frame 1 which carries a vertical lead screw 2 which can be raised and lowered by a manually-rotatable nut 3. The screw is adapted to support at its upper end a workpiece 4, a surface of which is to be subjected to hardness testing. The machine further includes an indenter spindle 5 which is co-axial with the screw 2, is situated above the screw and is guided for movement towards and away from the screw. To the lower end of the spindle 5 there is attached an indenter 6 having a pointed lower end for engagement with the workpiece 4.

The machine of Figure 1 further comprises a mechanism for urging the indenter 6 against the workpiece 4. This mechanism comprises a first lever 7 having at one end a fulcrum 8 on the machine frame 1. At a position spaced somewhat along the lever from the fulcrum, the lever is coupled to the indenter spindle 5. The mechanism further comprises a set of weights 9, so arranged that they can be suspended from that end of the lever 7 which is opposite to the fulcrum 8. Normally, as shown in Figure 1, the weights 9 are supported by a cam 10.

The machine of Figure 1 further comprises indicating means for indicating the magnitude of vertical movements of the spindle 5 and indenter 6. This indicating means comprises a further lever 11 which has at one end a fulcrum on the machine frame 1.

At its opposite end, the lever is coupled with a dial gauge 12 which provides a visual indication of movements of the spindle 5.

The lever 11 is coupled at a position between its ends with the upper end of the spindle 5, the lever being so arranged that vertical movements of the spindle are amplified and applied to the dial gauge 12.

In order to measure the hardness of the workpiece 4 by means of the machine shown in Figure 1, the lead screw 2 is adjusted until the indenter 6 is in contact with the workpiece and the dial gauge' 12 indicates zero depth. The indenter then bears a preliminary load which includes the weight of the spindle 5, the weight of the lever 7 and any further weights which may be applied to establish the required preliminary load. The cam 10 is then turned to apply the weights 9 to the lever 7, thereby applying an additional load to the indenter 6. When it can be seen from the dial gauge 12 that the indenter spindle has come to rest, the cam 10 is returned to its original position to remove the additional load.The increase in depth of the indentation caused by the temporary imposition of the additional load onto the preliminary load is then ascertained from the reading of the dial gauge 12.

The machine illustrated in Figures 2 and 3 has a frame 21 carrying a vertical lead screw 22 which is adjustable relative to the frame by a nut 23. On the upper end of the lead screw there is provided a support 24 for a workpiece 25 under test. These parts may be similar to the corresponding parts of the known machine illustrated in Figure 1. The machine of Figures 2 and 3 also has an indenter 26 which may be similar to known indenters.

In the machine of Figures 2 and 3, the indenter 26 is mounted on a lever 27 at one end thereof. At its opposite end, the lever has a fulcrum 28 on the machine frame 21.

In a case where the indenter is intended to be urged vertically downwardly onto the workpiece 25, the lever 27 is substantially horizontal, so that when the lever moves about the fulcrum 28 the indenter 26 will move along an arc of a circle which approximates very closely to a vertical path. It will be appreciated that the distance through which the indenter moves when the machine is in use is very small indeed, as compared with the length of the lever 27.

The fulcrum 28 is provided by four flexible strips of spring steel. Two only of these, 28a and 28b, are shown in Figure 3.

Typically, each strip has a thickness of 28 thousandths of an inch, a length of 121 inches and a width of 8 inch. The strip 28a is arranged vertically with its largest faces presented forwardly and rearwardly of the machine. Slightly less than a lower half of the strip overlaps wilh a rearwardly presented face of the lever 27 and this lower portion of the strip is rigidly secured to the lever. Slightly less than an upper half of the strip overlaps with a forwardly presented face on the machine frame 21. This upper portion of the strip is rigidly secured to the frame. The strip 28a is situated adjacent to one lateral extremity of the lever 27. A further one of the strips is similarly arranged adjacent to the opposite lateral extremity of the lever and is typically spaced from the strip 28a by a distance in the region of 2 inches. The strip 28b is arranged horizontally with its length extending from front to rear of the machine. Slightly less than the front half of the strip 28b overlaps an upwardly presented face of the lever 27 and this front porton of the strip is rigidly secured to the lever. Slightly less than the rear half of the strip 28b overlaps with a downwardly presented face on the frame 21 and this rear portion of the strip is rigidly secured to the frame. The fourth strip is similarly arranged, the horizontal strips being disposed between the vertical strips.

The flexible strips collectively provide for pivoting movement of the lever 27 relative to the frame about a horizontal axis which extends from side to side of the machine. It will be understood that the fulcrum 28 does not give rise to any frictional forces which oppose such pivoting of the lever 27.

The machine of Figures 2 and 3 further includes a mechanism for urging the indenter 26 against the workpiece 25. This mechanism includes a second lever 29 having at one end a fulcrum 30 on the machine frame 21. On a part of the lever 29 remote from its fulcrum there is suspended a set of weights 31. The mechanism further includes a rod 33 which is coupled to the lever 29 at a position between its ends but nearer to the fulcrum 30 than to the opposite end. The rod 33 is adapted to transmit downwardly directed force from the lever 29 to the lever 27 at a position between the indenter 26 and the fulcrum 28.

A roller 50 is provided for supporting the lever 29, in order to relieve the indenter 26 of the load derived from the weights 31. In Figure 3, the roller 50 is shown spaced from the lever 29 so that the additional load is applied to the indenter. The roller 50 is carried on a lever 51 which can pivot about a horizontal axis to move the roller from the position shown in Figure 3 into engagement with the underside of an end portion of the lever 29 remote from the fulcrum 30. Movement of the lever 51 is controlled by a dash pot 52 which limits the rate at which the additional load can be applied to the indenter.

A handle 53 is provided at the front of the machine to enable an operator to turn a cam or crank 32 from which motion is transmitted to the lever 51 to move the roller 50 into and out of engagement with the lever 29.

The machine further comprises indicating means for indicating vertical movement of the indenter 26. This indicating means comprises a third lever 34 which has near to one end a fulcrum 35 on the machine frame 21. The opposite end of the lever 34 is coupled to a dial gauge 36. At the end adjacent to the fulcrum 35 the lever 34 is coupled to the lever 27 at a position between the ends of the latter. The latter 34 is arranged to amplify movement of the lever 27 and to apply such amplified movement to the dial gauge 36.

The machine illustrated in Figures 2 and 3 is used in a similar manner to that already described with reference to the machine of Figure 1. Initially, the weights 31 are supported by the roller 50 and the indenter 26 is urged downwardly by a preliminary load which includes the weight of the lever 27 and of a further weight 37. When the cam 32 is turned, the indenter is subjected to an additional downward load derived from the weights 31. When the downward movement of the indenter has ceased, the cam 32 is returned to its initial position and the increase in depth of the indentation in the workpiece 25 caused by the temporary additional load is ascertained from the dial gauge 36.

In Figures 4 and 5, there is illustrated the indenter 40 and an adjacent end portion of an indenter lever 41 of a modified form of the machine illustrated in Figures 2 and 3.

The lever 41 corresponds to the lever 27 of Figure 2.

The lever 41 includes a turret 42 which is mounted on a further portion 43 of the lever for rotation about a longitudinal axis 44 of the lever. The indenter 40 is secured to the turret 42 and projects therefrom radially with respect to the axis 44. Also mounted on the turret 42 are certain components of an optical system of the machine. These components include an objective lens 45 which is spaced from the indenter 40 angularly about the axis 44. By turning the turret about the axis, a selected one of the indenter 40 and objective lens 45 can be directed towards a test area of the workpiece. The lever 41, including the turret 42, is hollow and light which passes through the objective lens is reflected by a reflecting mirror or prism 46 through the lever to further components (not shown) of the optical system of the machine. This optical system is arranged in a known manner to enable the diameter or other dimension of an indentation formed in the workpiece to be determined.

Attention is directed to the claims of complete specification No. 42405/75, Serial No. 1561732 which describes a machine as illustrated in Figures 2 and 3 hereof.

WHAT I CLAIM IS: 1. A hardness testing machine of the kind specified wherein the indenter is mounted on a lever, called herein the indenter lever, and at least one element of the optical system is also mounted on said lever.

2. A machine according to claim 1 wherein the indenter lever has a fulcrum adjacent to one of its ends and the indenter and said element are mounted on the indenter lever adjacent to its opposite end.

3. A machine according to claim 1 or claim 2 wherein said element is a reflector.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. front half of the strip 28b overlaps an upwardly presented face of the lever 27 and this front porton of the strip is rigidly secured to the lever. Slightly less than the rear half of the strip 28b overlaps with a downwardly presented face on the frame 21 and this rear portion of the strip is rigidly secured to the frame. The fourth strip is similarly arranged, the horizontal strips being disposed between the vertical strips. The flexible strips collectively provide for pivoting movement of the lever 27 relative to the frame about a horizontal axis which extends from side to side of the machine. It will be understood that the fulcrum 28 does not give rise to any frictional forces which oppose such pivoting of the lever 27. The machine of Figures 2 and 3 further includes a mechanism for urging the indenter 26 against the workpiece 25. This mechanism includes a second lever 29 having at one end a fulcrum 30 on the machine frame 21. On a part of the lever 29 remote from its fulcrum there is suspended a set of weights 31. The mechanism further includes a rod 33 which is coupled to the lever 29 at a position between its ends but nearer to the fulcrum 30 than to the opposite end. The rod 33 is adapted to transmit downwardly directed force from the lever 29 to the lever 27 at a position between the indenter 26 and the fulcrum 28. A roller 50 is provided for supporting the lever 29, in order to relieve the indenter 26 of the load derived from the weights 31. In Figure 3, the roller 50 is shown spaced from the lever 29 so that the additional load is applied to the indenter. The roller 50 is carried on a lever 51 which can pivot about a horizontal axis to move the roller from the position shown in Figure 3 into engagement with the underside of an end portion of the lever 29 remote from the fulcrum 30. Movement of the lever 51 is controlled by a dash pot 52 which limits the rate at which the additional load can be applied to the indenter. A handle 53 is provided at the front of the machine to enable an operator to turn a cam or crank 32 from which motion is transmitted to the lever 51 to move the roller 50 into and out of engagement with the lever 29. The machine further comprises indicating means for indicating vertical movement of the indenter 26. This indicating means comprises a third lever 34 which has near to one end a fulcrum 35 on the machine frame 21. The opposite end of the lever 34 is coupled to a dial gauge 36. At the end adjacent to the fulcrum 35 the lever 34 is coupled to the lever 27 at a position between the ends of the latter. The latter 34 is arranged to amplify movement of the lever 27 and to apply such amplified movement to the dial gauge 36. The machine illustrated in Figures 2 and 3 is used in a similar manner to that already described with reference to the machine of Figure 1. Initially, the weights 31 are supported by the roller 50 and the indenter 26 is urged downwardly by a preliminary load which includes the weight of the lever 27 and of a further weight 37. When the cam 32 is turned, the indenter is subjected to an additional downward load derived from the weights 31. When the downward movement of the indenter has ceased, the cam 32 is returned to its initial position and the increase in depth of the indentation in the workpiece 25 caused by the temporary additional load is ascertained from the dial gauge 36. In Figures 4 and 5, there is illustrated the indenter 40 and an adjacent end portion of an indenter lever 41 of a modified form of the machine illustrated in Figures 2 and 3. The lever 41 corresponds to the lever 27 of Figure 2. The lever 41 includes a turret 42 which is mounted on a further portion 43 of the lever for rotation about a longitudinal axis 44 of the lever. The indenter 40 is secured to the turret 42 and projects therefrom radially with respect to the axis 44. Also mounted on the turret 42 are certain components of an optical system of the machine. These components include an objective lens 45 which is spaced from the indenter 40 angularly about the axis 44. By turning the turret about the axis, a selected one of the indenter 40 and objective lens 45 can be directed towards a test area of the workpiece. The lever 41, including the turret 42, is hollow and light which passes through the objective lens is reflected by a reflecting mirror or prism 46 through the lever to further components (not shown) of the optical system of the machine.This optical system is arranged in a known manner to enable the diameter or other dimension of an indentation formed in the workpiece to be determined. Attention is directed to the claims of complete specification No. 42405/75, Serial No. 1561732 which describes a machine as illustrated in Figures 2 and 3 hereof. WHAT I CLAIM IS:

1. A hardness testing machine of the kind specified wherein the indenter is mounted on a lever, called herein the indenter lever, and at least one element of the optical system is also mounted on said lever.

4. A machine according to claim 3

wherein the indenter lever is hollow and the reflector is arranged to reflect along the interior of the indenter lever light approaching the reflector from a position spaced from the reflector in a direction transverse to the length of the lever.

5. A machine according to any preceding claim wherein the indenter and a part of the optical system including said element are mounted on the indenter lever for movement relative thereto between respective first and second positions, in the first of which the indenter faces a test area of the object to be tested and in the second of which the test area can be viewed through the optical system.

6. A machine according to any one of claims 1 to 4 wherein the optical element is mounted on the indenter lever for movement relative thereto into and out of an operative position and the indentation can be viewed through the optical system when said element is in its operative position relative to the lever.

7. A machine substantially as herein described with reference to and as shown in Figures Z and 3 of the accompanying drawings but incorporating the modification described with respect to and as shown in Figures 4 and 5 of the accompanying drawings.