DE4025135C1 - Pendulum striker mechanism for high difference measurement - has pulling device rigidly connected to pendulum hub, driven by pendulum and connected to drop height measurer - Google Patents

Abstract

The pendulum striker mechanism contains a first pulling arrangement (14) rigidly connected to the pendulum hub (4), driven by a pendulum (9) and connected to a drop height measurement device (20). A first rotary element (11) is rigidly connected to the pendulum in its hub and has a drive connection to a second rotary element (16) mounted at a fixed distance from the hub and rotatable about an axis (18) parallel to the pendulum axis. A second pulling arrangement (18,19) is attached to the second element at the same distance from its axis as the distance from the first arrangement to the hub. A measurement and guide rod (19) inserted in the measurement device is attached to the second pulling arrangement. The measurement results can be digitised and processed. ADVANTAGE - Enables height difference of pendulum to be determined more accurately and quickly than with conventional arrangements.

Description

The invention relates to a pendulum impact mechanism with a the first entrainer driven by the pendulum, which in a rigid connection to the pendulum hub of the pendulum is arranged and that with a drop height measuring device connected is.

Such a pendulum impact mechanism is known from DE-PS 5 18 969 known in which a drive plate on the pendulum rod is arranged on which a first horizontal arranged ruler is placed with which the height the starting position of the pendulum can be determined. To the driving disc takes the swinging of the pendulum a second horizontally arranged ruler with, that at the reversal point of the swinging pendulum the height then reached remains and so by reading the difference the height difference of the triggered Makes pendulum detectable. The different, mechanical preset rulers do not allow quick Sequence of impact attempts.

DE-GM 18 74 680 describes a pendulum impact mechanism, its drag pointer via a translating display has so that the angular resolution by a factor is improved on the order of three. they still has a tarnish protection in the form from a spring that the accuracy of the work again worsened.

In US 23 59 044 is a still sold today Pendulum impact mechanism described that an exchange  allowed the face and a braking device for the back swing of the pendulum.

The US 31 57 046 teaches a pendulum impact train with one simple drag pointer, taking the hammer of the pendulum below the segmented flywheel is attached.

Another pendulum impact mechanism is in US 27 78 219 described, which the residual energy determination of Halves allowed. It has a drag pointer on.

GB 3 76 726 describes a motor driven Impact machine in which the determination of climbing angles a pendulum is possible. These can be in the dead center of be detected by an operator.

From DE-OS 20 45 231 another pendulum impact mechanism known that one mounted in the pendulum hub Has coding disk. This coding disc has non-linear segmentation lines along their circumference, the length of each segment proportional to the drop height assigned to it Pendulum hammer is. About counting yourself relative segments moving past a measuring device the drop height can be determined directly. This device has the disadvantage that an error in counting the passing segments an uncorrectable wrong Measured value results and that the measured value acquisition in the area of 90 ° pendulum deflection critical in its resolution is.

From JP 63-1 13 342 in the Patents Abstracts of Japan, P-763, Vol. 12, No. 361 (1988)  a rotary potentiometer known, the output signal by the Hammer activity is determined.

DE-PS 9 20 152 teaches a registering impact tester, which attached one to a second pendulum Has writing device. With this it should be possible be a path-time diagram of the movement of the real one Record impact tester.

Finally there is a registration device in FR 9 20 928 described in which a pen over one on a coaxial to the pendulum hub Drum-attached paper is guided. About the location the start and end point of the writing line the paper which is the unrolled coat of the drum corresponds to the drop height in angular units readable, with the paper exchanged with every attempt must become.

From DIN 51 222 for pendulum impact testers it is known the height difference of a triggered pendulum To be determined using a differential angle reading.

The invention is based on this prior art based on the task of a pendulum impact mechanism to create the type mentioned at the beginning, which allows the height difference of a swinging pendulum with greater accuracy in shorter test repetition times to determine.

This object is achieved in that a first rotating element is provided, which with the Pendulum in the pendulum hub is rigidly connected and that in Drive connection at a fixed distance arranged to the pendulum hub, in a parallel axis  to the pendulum axis rotatable second rotating element which a second entrainer essentially in the Distance to the axis of rotation of the second rotating element is arranged is the distance of the first entrainer corresponds to the pendulum hub, and that on the first Drag means provided the drop height measuring device into which a measuring and guiding rod can be inserted, which is attached to the second tow.

The first, rigidly connected to the pendulum in the pendulum hub Rotary element with a first entrainer drives a second rotating element in opposite directions, on the a second entrainer similar to the first entrainer arranged at the same distance from the pendulum hub is. By connecting the entrainer Drop height measuring device is in the pendulum impact test the movement of a measuring and guiding rod can be detected, from which the drop height in the pendulum impact test can be determined from which all test parameters can be derived.

Advantageously, the rotating elements are interlocking Gears designed that a trouble-free Guarantee operation in an industrial environment.

The drop height measuring device is preferably a capacitive one Odometer designed, one on the second Insulating immersion sleeve attached in a cylindrical capacitor is insertable, the  thereby changing capacity is a direct measure of that Fall height is.

Further advantageous embodiments of the invention are characterized in the subclaims.

The following are exemplary embodiments of the invention explained in more detail by way of example with reference to the drawing. It shows

Fig. 1 is a schematic side view of a pendulum impact tester according to an embodiment of the invention

FIG. 2 is an enlarged side view of the pendulum hub area from FIG. 1, and

Fig. 3 is a block diagram of an evaluation device for differential height measurement in the pendulum impact tester according to an embodiment of the invention.

Fig. 1 shows a schematic side view of a pendulum impact tester according to one embodiment of the invention. The pendulum impact mechanism has a frame 1 , in the lower region of which a stop 2 is provided, on which a sample 3 extending at right angles to the plane of the drawing is arranged.

In the upper area of the frame 1 , a pendulum hub 4 with a horizontal axis of rotation is provided. The pendulum hub 4 is arranged vertically above the front stop plane of the sample 3 , which is indicated by the dashed line 5 .

At the teeter 4 is a pendulum rod 6 is fixed, which can oscillate freely around the horizontal pendulum axis of rotation. The length of the pendulum rod is z. B. 75 centimeters. At the lower end of the preferably thin but rigid pendulum rod 6 , a hammer 7 of large mass is attached. In the extension of the pendulum rod 6 , the percussion hammer 7 has a striking edge 8 in the center, the normal of which is aligned parallel to the instantaneous direction of oscillation of the pendulum. The pendulum rod 6 forms a pendulum 9 together with the hammer 7 .

The length of the pendulum rod 6 and the positioning of the striking edge 8 in the percussion hammer 7 is predetermined such that during swing of the pendulum 9, the blunt edge 8 meets the front stop surface of the sample 3 and, optionally, destroyed. The pendulum 9 swings in a plane parallel to the illustrated rack level 1 , so that a swinging of the pendulum 9 is guaranteed after the sample 3 has broken through beyond the vertical 5 .

On the percussion hammer 7 , one or more strain gauges 10 for detecting the force function during the swinging are arranged on the side of the striking edge 8 pointing away from the sample 3 .

A first gearwheel 11 is arranged on the pendulum hub 4 , for example with the aid of a bellows coupling, which rotates accordingly when the pendulum 9 swings. In the vicinity of the ring gear 12, which is only indicated in the drawing, a first fastening axis 13 is arranged in alignment with the pendulum rod 6 , which is aligned parallel to the pendulum hub 4 and onto which a driver element 14 is rotatably fitted.

The axis of rotation 15 of a second gear 16 is arranged on the connecting line 5 between the sample 3 and the pendulum hub 4 parallel to the pendulum hub 4 such that the ring gear 17 of the second gear 16 engages in that of the first gear 11 and thus the two gears 11 and 16 turn in opposite directions. The diameter of the gears 11 and 16 is z. B. 5 centimeters. Both gear wheels 11 and 16 have the same number of teeth.

A second fastening axis of rotation 18 is arranged in the vicinity of the ring gear 17 of the second gear 16 parallel to the axis of rotation 15 . The distance between the second fastening rotation axis 18 and the rotation axis 15 is essentially the same as the distance between the first fastening rotation axis 13 and the pendulum hub 4 for the first gear 11 . A measuring and guide rod 19 is plugged onto the second fastening axis of rotation 18 and extends through an opening in the driver element 14 .

When the pendulum 9 swings through, the toothed wheels 11 and 16 rotate in opposite directions at the same angular speed, the fastening axes of rotation 13 and 18 facing each other during the movement of the pendulum 9 over the line 5 in a minimum distance 40 , which is shown in FIG. 2 . This distance corresponds to the vibration level zero, ie the rest position of the pendulum 9 , in which it has no potential energy that can be released for the impact test. If the pendulum 9 is deflected in one direction or the other beyond the line 5 , this minimum distance 40 increases , the distance difference in height between the fastening axes of rotation 13 and 18 minus the minimum distance 40 being proportional to the deflection height and thus to the drop height of the pendulum 9 . This follows from the similarity of the triangles formed by the pendulum rod sections, the corresponding sections of line 5 and the imaginary horizontal lines at the level of the striking edge 8 or the fastening axes of rotation 13 and 18 .

When swinging the pendulum 9 , the distance between the mounting axes of rotation 13 and 18 increases beyond the minimum distance 40 , so that at the reversal points of the pendulum swing movement by measuring the distance between the mounting axes of rotation 13 and 18 directly on the effective drop height of the pendulum 9 and thus on the energy consumed when penetrating the sample 3 can be closed.

A drop height measuring device 20 is provided on the passage of the measuring rod 19 through the driver element 14 , which is shown in more detail in FIG. 2.

Instead of the gears 11 and 16 and hubs can be 11 and 16 which form a coupled pair of wheels 11 and sixteenth These are preferably connected in opposite directions via a drive. In a simple embodiment, this is not provided since the force exerted by the driver element 14 on the rod 19 rotates the second turntable 16 in the corresponding opposite direction during normal operation of the pendulum impact tester.

Instead of the turntables 11 and 16 , in another even simpler embodiment, radially extending connecting rods are provided, which are rotatably fitted on the axes of rotation 4 and 15 .

In all of the embodiments described above, the connecting axis 42 between the fastening axes of rotation 13 and 18 always runs parallel to line 5 .

FIG. 2 shows an enlarged side view of the pendulum hub area from FIG. 1, in which in particular the gear wheels 11 and 16 with the driver element 14 or with the L-shaped measuring and guide rod 19 are shown.

In the embodiment shown in FIG. 2, the head 20 is realized by a capacitive displacement sensor. On the driver element 14 , a hollow sleeve 21 is attached, which is arranged parallel to the line 5 . The orientation of the sleeve 21 parallel to the line 5 can be carried out by a positive guide or by a guide element 33 shown in FIG. 2. On the inside of the sleeve 21 , two capacitor foils 22 and 23 are applied, each of which has a connection which is led out of the sleeve 21 with a bushing 24 and 25, respectively.

The first upper capacitor foil 22 covers only a small part of the upper region of the sleeve 21 . The second lower capacitor film 23 lines most of the inner surface of the sleeve 21 and is only separated from the film 22 by a small insulating gap 26 .

A metallic round rod 27 is inserted into the sleeve 21 from above and is fastened centrally in the sleeve 21 by a stopper 28 . The round rod 27 has a length which corresponds to the length of the sleeve 21 , so that it extends to the lower edge of the lower capacitor film 23 .

The measuring and guiding rod 19 has an insulating, hollow immersion sleeve 29 which can be inserted into the round rod 27 and the sleeve 21 . Moving the immersion sleeve 29 in the sleeve 21 changes the capacitance of the capacitor formed from the round rod 27 and the film 23 .

In the circuit diagram, the reference capacitor 30 and the measuring capacitor 31 are shown, which are connected to a bridge circuit 32, not shown in the drawing, whose output signal, for. B. with a signal processing according to DE-OS 38 27 257.

To stabilize the drop height measuring device 20 , the guide element 33 can be provided, through which the guide rod 19 extends.

Another embodiment of the drop height measuring device 20 is a light barrier measurement, which is not shown in the drawing. A light source or a photodiode are arranged on two sides of the sleeve 21 . Between them, a transparent plate with opaque grid lines is arranged instead of the immersion sleeve 29 . In this case, the height is measured by counting the lines passing between the optical elements, the counting direction being reversed at the swinging point. Compared to the capacitive measurement, the light barrier measurement has the disadvantage that a very high counting rate can be detected and processed when the pendulum 9 swings over the line 5 at the maximum speed. The lattice constant of the rod is z. B. 50 microns.

Furthermore, the height measurement can be carried out by a magnetic length measuring device, in which the change in flux is detected for a magnetic rod moving along the sleeve 21 . The capacitive displacement sensor is replaced by a magnetic displacement sensor in the form of a moving coil.

In another embodiment, the drop height can also can be determined with a resistance transducer in which e.g. B. a rotary resistor and potentiometer with a Sliding contact is used.

In FIG. 2, also the position of the mounting axes of rotation is located during swing of the pendulum 9 13 and 18, wherein between the fixing axes of rotation 13 and 18, the minimum distance 40 is composed.

Fig. 3 shows a block diagram of an evaluation device for differential height measurement in the pendulum impact tester according to Fig. 1, in which the stroke speed v₀, the initial energy A₀, the work A _v and the calibration factor C of the force signal detected by the strain gauge 10 is determined. The analog height signal 50 present at the output of the bridge circuit 32 acts on a speed circuit 51 , an initial energy circuit 52 and a final energy circuit 53 .

The analog present height signal 50 is in a fixed value multiplier 54 , z. B. an amplifier module, multiplied by the constant 2 · g, where g stands for the acceleration due to gravity. This signal is erased in an eraser 55 and stored in a memory 56 with the aid of an initial trigger signal 57 at the start of the pendulum impact test. At the output of the speed circuit 51 there is therefore an analog speed signal 58 which is proportional to the root of 2 · g · starting height and thus the stroke speed v₀.

An analog voltage signal 60 corresponds to the pendulum mass m. It is amplified in a fixed value multiplier 61 with a factor corresponding to the acceleration due to gravity g. The signal, which is proportional, is multiplied by the height signal 50 in the circuits 52 and 53 in a multiplier 62 and 63, respectively.

In the initial energy circuit 52 , the signal proportional to the potential energy A₀ of the pendulum 9 is stored in a memory 64 with the aid of the initial trigger signal 57 at the beginning of the drop test. The initial energy signal 65 is thus present at the output of the initial energy circuit 52 and acts on an input of a subtractor 66 .

In the Endenergieschaltkreis 53, the potential energy of the pendulum is detected A₁ 9 at the reversal point of the pendulum swung through 9 by a Endtriggersignal 67 latches the output signal of the multiplier 63 to the turning point in a memory 68th The stored signal acts on the other input of the subtractor 66 , at whose output a signal 69 which is proportional to the energy A _v = A =-A 1 used in the impact test is present.

In a pre-factor circuit 70 , the signal 69 of the consumed energy A _{v is divided} by the signal 65 of the potential initial energy A₀ in a divider 71 . The output signal of the divider 71 is subtracted from an analog one signal 72 in a subtractor 73 . This output signal is erased in a further square root 74 and in a further subtractor 75 in turn subtracted from an analog one signal 72 , so that a pre-factor 76 :

is present at the output of the prefactor circuit 70 .

In the calibration circuit 77 , the signal 58 corresponding to the impact speed v₀ is multiplied by the mass signal 60 in a pulse multiplier 78 .

A signal 79 , which is proportional to the instantaneous force, can be determined from the strain gauge (s) 10 and acts on an integrating circuit 80 over the entire impact test. This circuit 80 is also acted upon by the start and end trigger signals 57 and 67 , the force integral R being determined over the test time lying between the times 57 and 67 . The corresponding time period could also be chosen to be shorter, since a force signal only occurs during the very short swinging of the pendulum 9 when the sample 3 breaks. The pulse signal of the multiplier 78 is divided by the signal proportional to the power surge R in a divider 81 , the result being multiplied by the factor 76 in a multiplier 82 and stored in a memory 83 at the end of the test using the end trigger signal 67 . This output signal 84 has the voltage value C of the formula:

proportional.

The calibration constant C can be determined from the test parameters v₀ - impact speed, A₀ - work supply or potential initial energy and A _v - used work as well as the additionally supplied signal of the power surge R determined with the circuit of FIG. 3. The analog output signal can be digitized and can be stored for further use in a data processing system, so that pendulum impact tests can be carried out in a simple manner in rapid succession, the results of which can be stored and called up for subsequent evaluations.

Claims (11)

1. pendulum impact mechanism with a first drag means ( 14 ) driven by a pendulum ( 9 ), which is arranged in a rigid connection to the pendulum hub ( 4 ) of the pendulum ( 9 ) and which is connected to a drop height measuring device ( 20 ), characterized in that that a first rotary element ( 11 ) is provided which is rigidly connected to the pendulum ( 9 ) in the pendulum hub ( 4 ) and which is arranged in a drive connection ( 12, 17 ) with a fixed distance from the pendulum hub ( 4 ) in one Is parallel axis ( 18 ) to the pendulum axis ( 4 ) rotatable second rotary element ( 16 ), on which a second towing means ( 18, 19 ) is arranged substantially at a distance from the axis of rotation ( 15 ) of the second rotary element ( 16 ), the distance of the first towing means ( 14 ) corresponds to the pendulum hub ( 4 ), and that on the first towing means ( 14 ) the drop height measuring device ( 20 ) is provided, into which a measuring and guiding rod ( 19, 29 ) can be inserted, which on the tw eiten entrainer ( 18, 19 ) is attached. 2. Device according to claim 1, characterized in that the axis of rotation ( 15 ) of the second rotary element ( 16 ) is arranged in a vertical extension ( 5 ) below the pendulum hub ( 4 ), the second towing means ( 18, 19 ) with parallel alignment ( 5 ) of the measuring and guide rod ( 19, 29 ) with the pendulum rod ( 6 ) has the smallest distance ( 40 ) to the pendulum hub ( 4 ) and to the first entraining means ( 14 ). 3. Apparatus according to claim 1 or claim 2, characterized in that the rotating elements ( 11, 16 ) are turntables. 4. The device according to claim 3, characterized in that the turntables ( 11, 16 ) can be driven in opposite directions at the same speed by a drive means. 5. Apparatus according to claim 1 or claim 2, characterized in that the rotary elements ( 11, 16 ) are intermeshing gear wheels which comprise the same number of teeth. 6. Device according to one of claims 1 to 5, characterized in that the drop height measuring device ( 20 ) has a capacitive displacement meter ( 21, 22, 23, 27 and 29 ). 7. The device according to claim 6, characterized in that the capacitive displacement sensor ( 21, 22, 23, 27 and 29 ) a capacitor sleeve ( 21, 22 ) attached to the first towing means ( 14 ) and arranged parallel to the vertical ( 5 ) , 23 ) and a central capacitor rod ( 27 ) arranged in the capacitor sleeve ( 21 ) and that an insulating immersion sleeve ( 29 ) is fastened to the guide rod ( 19 ), which between the capacitor surfaces ( 23, 27 ) in the capacitor sleeve ( 21, 22, 23 ) is insertable. 8. Device according to one of claims 1 to 5, characterized in that the head height measuring device ( 20 ) has a light barrier sensor. 9. The device according to claim 8, characterized in that the light barrier sensor has a fixed to the first towing means ( 14 ), parallel to the vertical ( 5 ) arranged sleeve ( 21 ) with a horizontally arranged light barrier and that a grid provided with a transparent rod is attached to the guide rod ( 19 ), which can be carried out between the light barrier, the grating having a multiplicity of opaque strips. 10. Device according to one of claims 1 to 5, characterized in that the drop height measuring device ( 20 ) has an inductive displacement sensor with a moving coil. 11. Device according to one of claims 1 to 5, characterized in that the head height measuring device ( 20 ) has a resistance transducer.