DE7044218U - Device for determining the compressive strength of spherical test specimens - Google Patents

Description

SNAM PROGETTI S.p.A., Milan / Italy

^ Device for determining the compressive strength spherical

Specimen. ~~~ 7

The invention relates to a device for determining the compressive strength of different spherical test specimens Diameter, with specimen holder and vertically movable punch.

Among those used to determine the strength against compression spherical materials means known in the art are those which include a Use a lever system with hydraulic actuation and devices that use a dynamometric system use, whereby the dynamometer is applied pngressively by means of a screw spindle handwheel.

The repeatability of the measurements is not possible with the first system; the measurement with direct display offers certain Difficulties and considerable effort

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these measurements.

The second type of the above-mentioned system lacks practical training, accuracy, and the possibility of repeating the measurements, the latter only being carried out visually and therefore completely subjectively. A common disadvantage of the two facilities is that the operations must be carried out by hand; The operator's presence and constant vigilance are required during the measurement in order to reproduce a standard measurement of the process or procedure.

There are therefore many errors in the measurements, the latter being influenced by the flexibility of the operating personnel will.

üri "indung3geT.ä3, on the other hand, is to create a device which makes it possible to automate these processes! and to make more accurate, similar, direct measurements due to their practicality can also be used in the so-called "glove box".

These errors are now avoided according to the invention in the case of front seal / of the type mentioned at the beginning by an electric magnet fixed on the same axis to the stamp, U.7. which is arranged concentrically with a winding and around the outside with a regular winding and by a limiter stop at the lower end of the electromagnet that creates a constant air gap.

^; h the structure according to the invention works the measuring

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- 3 g automatically and without errors,

The load causing the sample to break is measured, with electrical and electronic Way, the actual force acting at the moment of the specimen break can be determined and stored in the instrument. Using the Second regulating winding in the manner indicated, the linear increase in the supply current for the electromagnet is enabled at precisely the moment in which the current reaches the value required to break the sample.

The spherical test specimens preferably consist of uranium, thorium, plutonium, and mixtures of oxides spherical material of ceramic or metallo-ceramic type, which is hard or brittle, however Has strength against compression.

A slightly convex workbench component is useful for placing the spherical materials to be examined and an irrigation ring for clamping these materials and through an annular container receiving the sample holder Provision is made for the material fragments exposed to compression.

The invention will now be based on a preferred embodiment will be explained in more detail with reference to the accompanying drawings, in which:

Fig. 1 shows schematically a section through the device;

Fig. 2 is a usable circuit and <? Recording circuit; and

3 shows a working curve in the diagram.

In Fig. 1 sin electromagnet is shown schematically, which consists of a vertically movable element 1, at the top of which a work plane base part is screwed, which is slightly convex and is stored in an annular container 2, wherein the latter is used to collect the fragments emerging from the spherical ones subjected to compression Materials originate.

The spheroid materials or spherical materials, whose compression resistance is to be determined are placed on the slightly convex specimen holder 3 placed in order to enable precise centering of the spherical material; the latter will then clamped by means of a friction ring, which ensures precise clamping between the two working levels enables.

A limiter stop is made in the lower end of the electromagnet which enables the de-energized Electromagnet has a constant air gap

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and so only one calibration curve for large ones Series of spherical material to be examined

*. records. The air gap is denoted by 6 and is

; fixed by means of a nut 5 and a lock

nut held, which makes it possible for each measuring process of a fixed air gap independent of the diameter of the spherical material to be examined can be assumed.

Two coils are disposed around the electromagnet around, at a ner is a force coil 7, the other is a negelwicklung c .; both are electrically independent from each other, but dependent magnetically, since they are wound on the same magnetic circuit. The power winding 7 is fed with direct current with a sawtooth voltage, which varies from zero to the nominal voltage in a predetermined time and in this way it allows to progressively load the electromagnet and to expose the spherical material to be examined to the progressive compression, thereby violent Impacts or shocks that change the measurement are prevented.

The control winding 8 can by analog systems such as e.g. differential transformer as well as capacitive inductive and ohmic systems replaced v.'erden. The relationship between the load, expressed in kg, and the power delivered to the electromagnet is in Well known in electrical engineering as magneto hold-in force, expressed in joules / m

1 B ² S

where E is the magnetic induction,

£> a surface and

/ U _{0 represents} the absolute permeability of the air,

The following formula is used in practice

8 B ² S 10 ⁶

where the letters are the ones mentioned. Have meanings.

With changing excitation current and flow, the changes magnetic holding force according to the law mentioned above.

In order to perform the measurement, according to the invention the spherical materials placed on the sample holder 5, clamped by means of a friction ring 4 and then the "dtart" push button 14 is printed, whereby it becomes possible to feed the power or electric circuit.

The continuously burdened! Electromagnet begins, progressively the spherical üu examining material to squeeze.

During this phase di (! Cone winding θ has a constant

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70U21827.6.7 / *

electromotive force (- e = d 0 ) on the so

as it is, exposed to a constant change in flow is, the change in the excitation current (di a K) am

Electromagnet and the air gap are constant.

If the spherical material breaks, there is a rapid change in the air gap and so with the same excitation current a change in flux, the magnetic resistance of the circuit is reduced; from this it follows that a voltage pulse (- e = d | _),

the electric motor force superimposed on the control winding is generated.

In Pig. 2 is an amplifier and recorder block diagram generated by an amplifier 9, a sawtooth generator 10, a logic circuit 11, an acoustic and optical alarm device 12 and is formed, whereby the occurred break of the spherical material is signaliaig.

White push buttons "On" and "Zero setting ¹¹ " are labeled x4 and 15.

The voltage pulse generated at the moment when the spherical material ruptures is transmitted by the amplifier 9 reinforced according to FIG. 2, which regulates a logic circuit 11 which operates the actuating member 10; the latter interrupts the increase in the sawtooth tension at the precise moment when the spherical material breaks occurs and thus the excitation current remains on the electromagnet on the fractional value.

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In . esem pall it becomes possible on the ammeter the excitation current, which leads to the breakage of the spherical material, to be read and from this by means of a Calibration curve to find out the breaking load in kg.

It is possible to calibrate the scale in kg and in this way read the value directly in kg.

Pig. 3 shows a graph where the abscissa is divided into kg and the ordinate is divided into amperes.

The electric agent's linear rendering curve alone Is used. The breaking of the spherical material is triggered by an acoustic and optical alarm device 12 and 13 in Pig. 2 signals.

The excitation current causing the breakage of the spherical material is displayed on the measuring device, until the operator presses the "reset" button 15, which automatically resets the meter to zero the latter is then ready for a subsequent measurement in this way.

If the mechanical strength of the spherical material reaches the maximum stress on the electromagnetic magnet, bo, an automatic device resets the device to zero without any signals and to this white-be the device is not damaged.

In view of a concise description, only that which is considered to be absolutely essential for the invention has been included in the Description added; the explanation was only given based on a single embodiment, without the invention being limited thereto.

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Claims (3)

SNAi? PRCG-EiTI S, p.A. 11/30/1973 Case 3 G 7C ■ 213.1 PROTECTION CLAIMS 1. Device for determining the compressive strength Spherical pro "body of different diameter with specimen holder and vertically movable Stamp, characterized by a coaxial with the stamp, on this fixed electric agent (1) to which concentric egg / .e power winding (7) and around this a gel winding (8) is arranged around it; and by a constant air gap (6) generating Limiter stop (5) ani under ei end dea Electric Agents (1). 2. Device according to claim 1, characterized in that the spherical test pieces made of uranium, thorium, Plutonium, oxide mixtures and spherical material of ceramic or metalloceramic type, which is hard or is brittle but has compressive strength. 3. Device according to one of the preceding claims, characterized by a slightly convex working plane component for placing the spherical materials to be examined and through a friction ring for Clamping these materials and through an annular container (2) receiving the sample holder (3) Recording of the material fragments exposed to compression. Protection claim Qü It. Bl ο Ί zu <. "; ■■ ':. ·