DE2260614A1 - HARDNESS TESTING MACHINE - Google Patents

Description

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S.K.F. COMPAGNIE D'APPLICATIONS MECÄNIQUES, in Clamart (Hauts-de-Seine) France

Hardness testing machine. Priority: France, December 21, 1971

The technical sector of the invention is that of hardness testing machines.

The previously known machines, which operate on the so-called · "Rockwell" -Prüfmethode with the corresponding _penetrator; should enable the. to press the pyramidal tip of a diamond onto a workpiece. This penetration body is first subjected to a preload and then, with a reduced penetration speed controlled by a shock absorber, a main load which is withdrawn after a certain period of time. The test is ended by reading the measured value of the remanent penetration depth on a dial indicator, which is caused by the action of the main mass.

In the known equipment, the indenter is mounted on a sliding device, generally a ball cage Supported by two pivoting levers mounted on ball bearings or knives via knife joints. One of the levers carries the regulating weight,

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which forms the preload and is located on the same side as the support knife on the penetrator in relation to its self-aligning bearing, while this lever at its opposite end constantly actuates the boiler pin of a precision pointer.

A second lever is on the same side of its self-aligning bearing with a trimming knife above the penetrator, in an intermediate window of this latter, provided, which has a predetermined play, a Shock absorber and then a device for permanent hooking which has the main load forming mass.

All these organs, such as the roller joints, the sliding cages and others, have the effect, while at the same time prescribing an increase in accuracy, the introduction of numerous uncertainty factors which make this alleged improvement illusory. In addition, the mechanism is of a complex and expensive type. Furthermore, the speed and the time of application of the preload is uncertain, while the penetration rate of the load, which is achieved by the Stoesdämpfer, turn just fall is quite uncertain, leaving the ^A nwendungedauer the initiative of the operator and is not constant. This unit of uncertainties is also disadvantageous for the fidelity of the measurement.

It is a particular object of the present invention to remedy such disadvantages.

For this purpose, the invention comprises a testing machine of this type in which a single lever continuously controls a regulating weight for preloading carries, is provided with organs for coupling to at least one main mass and with organs for attachment to an indenter, the called lever is mounted with a self-aligning bearing, which is formed by a pin with flexible, but inextensible, crossed blades, the is connected to the penetrator by a flexible and inextensible blade, which preferably operates under compressive stress while

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the indenter itself, as well as a rod carrying the main mass, is provided with guides, each formed by at least one pair of flexible and inextensible blades, which are also parallel are arranged.

An electrical coupling is assigned to the penetrator, which enables it to be connected to the indenter at any time To connect the measuring pin of a precision pointer

The rod carrying the main mass is assigned to a ram that rests on a nooke to determine the test program different attempts in succession lifting the lever and of the indenter, the lowering of the latter alone, then the use of the preload and then the main load for time intervals, which are determined by the operation of a motor and by an adjustable timer, finally to the above first to return to the aforementioned position in order to lift off the indenter as soon as the remanent penetration depth has been read off the indicated dial indicator is.

It is advantageous to run the work cycle at the same time to control the electrical coupling of the precision pointer and an illumination of the dial of this device «

A trigger is provided to start the cycle that is associated, thanks in particular to that associated with the rotating cam Contacts until it is terminated.

Furthermore, a machine designed in this way can easily be provided with a composite main mass, the elements of which are represented by a suitable control device can be brought into and out of function.

As for the indenter itself, its tip can be protected inside a movable test specimen support, whereby this support by the named test object elastically in a stop

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position can be shifted.

Electrical contacts can also be provided on this level, which enable the automatic start-up of the measurement » Offer cycle as soon as the test object located under the indenter is pressed.

The above-mentioned arrangements enable considerably improved fidelity to be achieved, initially on the Level of the elements of the mechanism and then on that of the fully mechanized and repeatable cycle flow. Furthermore, these fidelity advantages are accompanied by a significant structural simplification, with which the considerable increase the accuracy is compatible.

The invention is explained below by way of example with reference to the drawings. Show it :

1 shows a schematic representation of the mechanism under consideration;

Fig. 2 shows in section a head of the machine thus set up; 3 shows a section along the line IH-III in FIG. 2; Fig. K is a front view of the machine head it f Figure 5 is a view of the underside of the penetrator protector;

Fig. 6 and 7 in a schematic representation of two variants of the Arrangement for controlling the weights that can be used alternately or together as main mass variators according to the hardness ranges under consideration.

As can be seen in Fig. 1, the testing device has a penetration body 1 which is provided at its end with a pyramidal diamond tip 2, this penetration body 1 being connected to a pair of flexible but inextensible blades 3 and k of fairly great length, which are parallel to each other are arranged and the ends opposite the penetration body receiving ends at fixed

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Points 5 and 6 are anchored. This penetration body 1 is in the axial Direction connected by another flexible sheet 7, which is inextensible and able, also without change in length under compressive stress to work and by fitting on the one hand to the penetration body 1 and on the other hand on a rocker arm 8, in the vicinity of a pivot pin 9 «which appears at one end of the rocker arm. This cone is also made up of two rows of leaves arranged in a cross embodied that are flexible but inextensible and incompressible and at the same time are fitted on the rocker arm and fixed points.

The rocker arm 8 comprises a mass 10 which is adjustable in its position and which is intended to preload the tip 2 of the indenter to effect on the surface of a test body «On the opposite side of the pin 9 is the free end of this rocker arm 8 provided with a Hing 11 with narrow inner bearing surfaces, into which a hook 12 at the end of a rod 13 enters with play. These Rod 13 is made elongated, more flexible, but inextensible by a pair Sheets 1 * t and 15 held and guided, the ends of which are fixed with each other with the rod 13 connected annular flanges and with fixed anchors 16 and 17 are bladed together. This rod carries you The main load forming plate 18, and its lower end, on which the hook 12 opposite side, is provided with a should 19, which with different successive starts of a rotatable cam disk 20 controlled by a drive element can interact.

An electromagnet 21 is between the penetrator 1 and the Measuring pin of a precision pointer 22 is arranged. This electromagnet is attached either to the plunger or to the indenter and can operate a flexible tongue when tightening, causing said indenter is firmly connected to said measuring pin as soon as the electromagnet is excited. This tongue is apparently firmly attached to the Measuring pin connected when the electromagnet is mounted on the indenter

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is animal. The reverse situation can also be considered.

The organs described above can conveniently be accommodated in an arm 23 ″ which is arranged as a cantilever and which belongs to a machine frame, in a column 2k that supports this arm overhang, and in a base 25 carrying this column, this base also receiving a nut 26, which with Actuating arms is provided and in which a spindle 2? is arranged, which carries a plate 28 on its head, which is coaxial with the spindle and the penetration body.

In the base 25 there is also an electric motor 29 for driving the cam disk 20, the mode of operation of which is described below. The plate 18 forming the load can, for example, be assigned to other masses 30 and 31 which can be raised as desired. You can rest on the said plate or be lifted from it under the action of individual, slightly flexible cable pulls 32 and 33, which are coupled to a pulling drum 3 * f, which is actuated by a button 35. This button is located on the head side of the arm 23 next to a reading window 36 of the dial of the precision pointer 22 » Next to the button 35 there is another button 3 in this head? intended for setting a timer for operating the motor 2 $. Thus, the apparatus thus described has a true breadboard ait adjustment and Ableseorganen that allow the operator an easier work and a secure control (see ^F ig. Ό "

As can be seen in Figs. 2 and 5, the tip of the penetrator 1 is protected by a cover sleeve 38 which comprises a projection on which a projecting conical sleeve appears, said projection being provided with three set screws 39 which are located under the surface of the Arm 23 can be brought to the stop. This protective element is mounted on a plate ko made of elastic material, which is made pliable by graduated circular sector slots to increase flexibility. This plate is attached to struts on its circumference by screws * f1.

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ter the said surface of the arm 23 attached.

To operate the cables 32 and 33, the drum 34 'is provided with a bracket that is common to the two cables, which are guided through separate deflection eyes. An eyelet 42 for the cable 33 is located under the pivot of the drum 34 * during eiiie other eyelet 43 for the cable 32 protrudes laterally. The drum itself is provided with a number of bores 44 with which a not shown sliding locking finger cooperates.

As can be seen in Fig. 7, another system could be connected be used with the button 35, namely profiled fingers 45, the slack for example a cable 32 between the fixed Attachment point 46 and a deflection eye 47 can change. Of the The advantage of such a system is that it enables a mode of operation without locking devices, since the friction of the fingers 45 below the cable is sufficient to ensure the safety.

The mode of operation of such an arrangement is then as follows:

An operator places a test body on the plate 28 and lets this rise so far under the action of the nut 26 on the spindle that it coincides with the face of the conical extension of the Protective element 38 of the indenter 1 comes into contact.

The tightening of the nut 26 can continue until contact between the stop screws 39 and the corresponding surface of the arm 23 will. <

Actuated by a special switch-on button, not shown, or by means of a protective element 38 which comes to a stop through this Contact starts the test cycle by switching on the motor 29. The highest slope of the cam 20, which it over the plunger 19, the rod 131 enabled the hook 12 and the upper bearing surface of the ring 11, to keep the Upitze dt-ß indenter inside this protective organ,

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can descend the plunger 19, whereby the hook 12 to the ^A of the upper bearing surface of the ASK ring 11 is brought as soon as the tip of the indenter comes into contact with the specimen. This placement takes place freely under the action of the preload caused by the mass 10.

In addition, this application of the preload takes place more gently Way and at a controlled speed under the action of the slope of the slope, which causes the highest run-up of this cam 20 with a Intermediate call connects. Furthermore, the length of this intermediate stop determines the controlled application duration of this preload.

At the downstream end of this intermediate stop, the The plunger 19 is brought to a downward movement on a lower run-up of the cam 20, which means that the hook 12 is supported on the lower part of the ring 11 and thus the application of the additional load provided by the mass of the plate 18 to the rocker arm 8 and the penetration body 1 is equivalent to. In this case, too, the load is applied at a controlled speed, which corresponds to the profile given at the connection between the intermediate approach of the cam 20 and the lower approach.

For this situation with the lower approach of the cam 20 fixed on the plunger 19, a microswitch also interrupts the mentioned Cam clamped actuator supplies power to the electric motor 29 and turns on the timer, which is set by the button selected position is regulated. This latter determines the downtime of the engine and, consequently, the duration of the application of the full of load given to masses 10 and 18 before releasing it again, to turn on the motor 29 again and bring a rise under the plunger 19, which returns the device to the starting position, that is, the plunger 19 on the upper contact of the cam, the rocker arm 8 is supported by the hook 12 and the penetration body 1 is completely lifted off the Test item.

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At the moment the timer is kept, one lights up Lamp for illuminating the dial of the precision pointer 22 to draw the operator's attention to the need to monitor the To direct the instrument and the reading.

It must also be noted that a contact assigned to the nooks 20 in the vicinity of the outlet-side end of their intermediate approach the circuit of the electromagnet 21 closes the penetration «· body 1 firmly connects to the measuring pin of the dial indicator 22, the Circuit of the electromagnet is interrupted as soon as the rotation of the Cam 20 the rise for the final lifting under the plunger 19 leads.

It can thus be seen that from the moment it is switched on of the measuring cycle at the operator only the moment of reading has to wait, which by the internal illumination of the fine pointer 22 is shown.

Depending on the hardness scales, the operator can press button 35 Adjust the masses that form the main load for the measurement by moving the plate i8 either with the mass JO alone or, if necessary, with the mass 31 alone, or with the two masses 30 and 31 overloaded will. Likewise, he can determine the time of application of the indenter 1 regulate under full load by setting the timer accordingly, which is done using button 37. The contact for the start of the cycle can either through an independent button or through one of the protective devices 38 associated contactor are closed. This protective organ can also be provided with a radial slot ^ 8, the access to a screw to attach the diamond tip to the Penetrator 1 allows.

It should be noted that in the case of using the Masses 30 and 31, the corresponding cables 32 and 33 are relaxed, but only a negligible influence on the effect of the said Exercise crowds.

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On the other hand, the protective element 38 plays an effective role, since the diamond tip is not exposed even when the machine is idling due to the assembly on an elastic plate kO. The screws 39 also allow an exact adjustment of the position of this tip in relation to the penetration surface of the test specimen.

It is obvious that for the pin, the guidance of the rocker arm and the rod as well as for the transmission between the rocker arm and penetrators the use of flexible but inextensible blades instead of roller bearings, knives, ball cages and the like the arrangement with a single lever and its measuring accuracy while at the same time significantly simplifying the construction the machine obviously improved.

The same applies to the use of a simple rocking lever instead of two classic levers, as well as for the direct measurement of the measurement on the indenter.

A very significant advance which increases the fidelity in a decisive way and the efficiency in the case of series hardness tests considerably improved, results from the complete automation of the sequence of the cycle brought about by the use of a motor-driven cam is achieved, which uses the preload and the load in conjunction with that of a timer fully controlled, which regulates the duration of full load operation, this control includes that of the infeed speeds, thus eliminating the on the previously known machines required shock absorber allows.

The electrical coupling between the indenter and the measuring pin the dial indicator finally enables that on the classic machines to avoid the traditional previous "three hand rotations" and only use the precision pointer for the useful duration and only with one to use exactly miniaalen hub.

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It goes without saying that, without departing from the scope of the invention, Modifications can be made to the embodiments described above by way of example.

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Claims (12)

PATENT CLAIMS Π ·) - Hardness testing machine for the method and equipment for testing the "Sockwell" hardness, characterized in that it comprises a single lever which continuously has a regulating weight for preloading which appears in relation to a fulcrum of the lever on the same side as organs for fastening said lever on one Penetrators and, at the end opposite the pivot point, such as members for attachment to a main mass, said pivot pin being formed by a hinge of crossed leaves, said penetrator, like the main mass, being guided by leaves and the Organs for fastening said lever on said penetrator also consist of a sheet, all of these sheets being attached their ends fitted and are elastically flexible in the transverse direction, but inextensible in the longitudinal direction. / 2. - Machine according to claim 1, characterized in that the main mass is provided with a hook that is under play with the Narrow bearing surfaces of a fastening ring cooperates on the End of said lever is worn. 3 * - machine according to claim 2, characterized in that said main mass is assigned to a device for motorized raising and lowering. k. - Machine according to claim 1, characterized in that an electrically operated coupling is switched on between the penetration body and the measuring pin of a precision pointer and can thus be coupled directly to the latter. 5. - Machine according to claim k _t, characterized in that it is provided with organs for displaying the duration of the measuring cycle in the course of the test, in particular by illuminating the dial of the fine pointer. 309827/0349 6. - Machine according to one of the preceding claims 1 to 5> characterized in that they have organs for changing the test conditions and in particular comprises an adjustable timer which stops the actuators of the main mass for a predetermined period as well as organs for changing this main mass itself. 7. - Machine according to one of the preceding claims 1 to 6, _ characterized in that it comprises a protection device for the tip of the penetration body, which is elastically attached to the machine frame and includes stop members that allow the displacement of this protective device under the action of the delivery of the presented Limit the test item. 8. - Machine according to one of the preceding claims 1 to 7t characterized in that the organs for actuating the main load are set in rotary motion in particular by a motor Cam disc are formed, which has a plurality of runners, which at least three stages with mutual progressive connections show, the cam disc having a plunger at the foot of a rod supports, which carries a plate, which forms one of the elements of said main load, and said motor electrically through starting elements, Organs for temporary shutdown and organs for shutdown is controlled in the end position. 9 · - Machine according to claim 6 and 8, characterized in that additional masses forming the said main mass for organs Suspension and for setting down on said plate are assigned, these organs being inextensible, light and flexible cables for suspension include the said additional masses. 10. - Machine according to claim 9 »characterized in that Each cable loom in the machine mentioned is assigned organs that allow the active strand length to be changed and organs for locking the position include with positive or non-positive actuation. 11. - Machine according to one of the preceding claims 1 to 10, ill » characterized in that it comprises a base which is supported by a Column old is connected to an arm and contains the cam disk and its motor, the column enclosing a rod which runs out on one side into a pestle with a roller and on the other side one Has hook for cooperation with a ring at the end of the lever, a main mass plate being arranged in the central area of this rod, whereas said arm holds the lever, the hinge and fastening blades, the penetrator and the regulating weight for the Contains preload, the head of said arm forming a control panel on which an organ for setting the timer, an organ for Control of the main mass and a window for reading the dial indicator appear. 12. - Machine according to any one of the preceding claims 1 to 11, characterized in that it comprises means for switching on the cam disk motor with control separate from or integrated into the protection device for the tip of the penetrator. iflOQil / λ ο / a Blank page