DE1648448B1 - Flexural strength tester for foundry core sand mixtures - Google Patents

Description

1 648 44a

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The invention relates to a flexural strength not provided, this known device is not for Tester for foundry core sand mixtures, suitable for measuring the flexural strength of a material, a produced from the mixture to be examined. The object of the invention is to provide a The test bar with a square or prism flexural strength tester for foundry core sanding tables To create a cross-section on two in a certain 5 mixtures of the type mentioned above, Rounded and spaced apart under the heavy-duty cutting edges prevailing in a foundry and works quickly and accurately in the midst of adverse conditions and at see the cutting edge through one on a measured value - especially the pressure cutting edge and others Movable pressure cutting edge acting on the display guides the links acting on the measured value display in this way is burdened. io are that a falsification of the measurement result

Such known flexural strength testing devices are excluded.

The task is solved by the following partial-

motor driven. The flexural strength value must be wise on its own or in combination with one another

can be read off a finely divided scale. known features that between an upper

If there is a lack of attention and concentration 15 and a lower slide, an axially acting one

of the device operator is a wrong reading calibrated spring member is provided that the upper

of the measurement result is very easy. Further slide by an electrically driven one

Disadvantages of such devices are that the cast cam or a positive cam control

The dust generated by friction moves very far into that which is as linear as possible in the area of the test pressure

Inside the devices can penetrate and that the 20 thrust cam is driven that the drive

Devices for a quick check of the content that is assigned to an electrical relay circuit, which

the molding machines continuously inflowing sand - this is maintained after switching on for so long,

Bucket work too slowly. until the aforementioned cam or another

In a neighboring area of the material-driven cam the drive motor again Testing it is known that the flexural strength of construction 25 switches off, that the lower wood of the spring member check a rectangular cross-section. The carriage to be driven holds a pressure shaft that stops The body to be tested lies on two in one face of the pressure cutting edge that bears on know distance from one another arranged supports the printing shaft a number of in its movement and is between these over a role of a direction of movement one below the other or one behind the other subject to variable bending loads. With larger than 30 step contacts for an indication of certain bending points As the load increases, contacts are arranged according to strength groups and that the closed to each other until the deflection of both carriages by means of profile rollers along the vertical has reached a certain limit and the load columns run.

is taken away. In this way, all through the inventive solution of the problem Test pieces bent by the same amount and the 35 are not only known features from neighboring force, which is necessary for this deflection, is th areas of materials testing, especially the measured and displayed in steps. The force measurement step-by-step display of flexural strengths in the takes place via a U-shaped bent spring, taken over at the test device according to the invention. About that the roller is attached to one leg via a lever by using two carriages, is and on the other leg of the load 40 between which an axially acting calibrated spring necessary force is applied. member is arranged and by means of profile rollers

This device has the main disadvantage that vertical columns are guided, that the pressure that as a result of the compression, the roller only cuts perpendicularly towards the test rod the spring moves sideways under load. This is so that the test rod is always exactly in the middle However, lateral movement is strained when testing 45 between the two support edges Foundry core sand mixes not acceptable because it becomes. The attachment of the spring link to the two Firstly, through this lateral movement, the measuring slide ensures a purely axial load on the spring result would be falsified, in particular as a result of the member, so that a falsification of the measurement result short distance between the support cutting edges, and two is avoided in this way.

at least one impermissible damage to the test rod 50. Advantageous embodiments of the invention

can occur. The test devices required for the known device are listed in the description of the drawing.

agile role also allows an exact determination exercise explained in more detail. It shows

of the load point not to. The in the known Fig. 1 is an elevation of the new test device, sch-

th device used a spring, which at the same time automatically displays,

of the measurement result is actuated, is therefore for the test 55 F i g. 2 the upper end of the test rod support

not suitable for foundry core sand mixtures. buck of the device according to FIG. 1 in section according to the

It is another device for checking different line Π-ΙΙ from F i g, 3,

Materials known in which a pressure cutting edge on Fig. 3, the upper end of the sample rod support

the end face of a pressure shaft is provided, jack of the device according to FIG. 1 in side view,

between an upper and lower holding 60 F i g. 4 a roller guide for the drive and

tion has an axially acting spring member and shaft slide of the device according to Fig. 1, as a single

which is drawn by a motor-driven cam with a unit in axial section,

Relay circuit is driven, which drives the drive F i g. 5 a spring lock for the measuring spring of the

is maintained until a co-driven device according to Fig. 1, as a detail in axial section

Cam switches off the drive motor again. The 65 drawn,

Spring member should only the rotating pressure F i g. 6 an adjustable pressure cutting head for cut with constant force against the to be tested the pressure shaft of the device according to Fig. 1, in side material press, a measurement of this force is evident,

F i g. 7 a drive cam for the pressure shaft of the arrangement according to Fi g. 1, in side view,

F i g. 8 a positive cam control for the pressure shaft of the device according to Fig. 1, cut in the AxiaK,

F i g. 9 is a circuit diagram for the electrical display of the device according to Fig. 1,

10 shows a double arrangement of the device according to FIG. 1, in a schematic representation.

In the embodiment according to FIGS. 1, 2 and 3 stand on a base plate 1 with two with an upper support cutting edge 2 and one behind this Support brackets 4 provided with lying stop 3 for the test bar 5 to be tested for its flexural strength.

In the middle over the through the two support cutting edges 2 a certain length of support floats a pressure cutting edge 6 of a shaft 7 parallel to this, followed by a carriage 10 running along two columns 9 by means of profile rollers 8 (FIGS. 1 and 4) protrudes below. The two columns together with an upper and lower plate 11, 12 form a rigid one Frame. The shaft 7 penetrates a hole 13 present in the lower frame plate 12 and his The point of passage is through a harmonica sleeve attached to the underside of the plate and to the shaft 14 sealed dust-tight.

A helical spring 15 serving as a measuring spring sits on the shaft slide 10 and a two-part on it ter, also by means of profile rollers 16 along the Säu ^ len 9 running carriage 17, of which a cylindrical drive shaft 18 through a hole 19 in of the upper frame plate 11 protrudes into the range of motion of a cam 20 whose shaft 21 is driven by an electric motor 22.

The distance between the two carriages 10 and 17, the clamping height of the spring 15 and its preload can be adjusted by a screw shaft 23, which at its lower end with an elastic Stop 24 is provided for the shaft slide 10, an existing hole 25 in this free penetrated and can be screwed into a threaded hole 26 in the drive carriage 17 as deep as desired.

The spring 15 can be inserted loosely between the two carriages 10 and 17. However, it is better a special spring holder provided on the mutually facing sides of the slide, e.g. B. after F i g. 5. For this purpose, the two carriages 10, 17 each have a recess 27. Both wells 27 lie flush on top of each other. In this are by means of screws 28 easily detachable spring plate or Locking sleeves 29 used with a collar 30 or spring plate on the carriage end faces rest and on which the ends of the spring 15 are pushed.

The coarse axial adjustment of the pressure cutter 6 takes place by means of a fine-thread pin 31 which is screwed into an end bore of the shaft slide 10 and is fixed there in its height position. For a stepless axial adjustment of the pressure cutter 6, it is manufactured as a plug-in part 6a according to FIG.

It is desirable that the thrust curve of the cam 20 in the range of the test pressure as possible time-linear. This can be achieved in that the cam 20 is designed as an eccentric and the Measuring spring 15 is dimensioned so that the signal contacts described in more detail below in the initial area the sinusoidal thrust curve can be arranged, which is still approximately linear in time. But it is also possible to give the cam 20 a shape as shown in FIG. 7 is shown. Here the distance decreases 34 between the central longitudinal axis 35 of the camshaft 21 and the lateral surface 36 of the cam 20

ίο proportional to the angle of rotation over half the circumference of the cam 20, while the other half is symmetrical to it.

The return of the carriage 17 to the starting position is carried out either by an intermediate the carriage 17 and the rigid frame provided return spring, not shown, or by an inevitable control 37 according to FIG. 8. The cam 20, which is designed here as an eccentric, guides is, via a roller bearing 38, the ring 39, which is connected to the drive shaft 18 and thereby with the Slide 17 is firmly connected. Has the cam 20 the in F i g. 7 is a prerequisite for a positive control that all diameters of the cam 20, which the central longitudinal axis 35 cut the camshaft 21, same length on-r point. During the upward stroke of the slide 17, the shaft slide 10 is moved by the screw shaft 23 with moved up.

The device described above is in a thin-walled enclosing this dust-tight on all sides Housing 41 housed, with the exception of a missing front wall portion between the lower Frame plate 12 and the base plate 1, so that the compartment 42 containing the supports 4, in which the Print shaft? protrudes dust-tight from above, easily accessible from the front of the housing is.

The mode of operation of the device described so far emerges when considering FIG. 1

4Q without further ado. As soon as the cam 20 drives the drive ^ slide 17 moved down, the spring 15 and the shaft slide 10 is moved down until the Shank blade 6 rests on the test rod 5 and this initially moves the shank slide 10 further prevents. From then on, the spring 15 is compressed until its tension the Reached the breaking limit of the test rod, the rod breaks, whereupon the shaft slide 10 first up to the stop 24 of the screw shaft 23 jumps further down and after the reversal of movement at the top, the two carriages 10, 17 with the spring 15 also move upwards again.

The fragments of the test rod 5 are either removed by hand or can be seen in the base plate 1 of the housing a failure opening in front of which z. B. a leading to a collecting container Funnel or the like. Can connect.

As already mentioned, it is sufficient to know which strength value group or quality class is to be used investigating core sand mixture produced test rods 5 belong in order to provide information about the possibility of using the foundry sand cores produced from the mixture in question. For this purpose z. B. on the front of the housing 41 above the freely accessible from the front Subject 42 z. B. three signal lamps 43, 44 and 45 are arranged. These are sent to the two carriages 17 and 10 arranged step con

5 6

bars 46, 47 and 48 one after the other to light up In a similar manner, the switch works as soon as the drive slide 17 approaches the device, when in the area of higher strength values of the shaft slide 10 the step contacts 47 and 48 close at a certain distance from the test rod 5. The approach begins as soon as the sen, the relays g and A with their associated pressure cutting edge 6 touches the test rod 5 and 5 working contacts g _v g ₂ or A ₁ , A ₂ address thereby the shaft slide 10 so long on a white and the lamps 44 and 45 are prevented from lighting up in the downward direction until the pro men.

bestab5 breaks. 1 shows that the safety contact e _x is known during the test that each step switch 46 to 48 has a process closed and that a correct force is only assigned when the device is ready to test, and thus that the associated device of the device is opened. This prevents the signal lamps 43 to 45 from indicating a certain level of stability due to accidental activation of the command value of the test rod 5. switch d during a test process the from

By the circuit diagram of Fig. 9 of the drawing contact ^ interconnected lines k is the circuit diagram of the electrical device and m are separated from each other, which is shown in advance. The reference numbers in FIG. 1 15 early extinguishing of the signal lamps 43 to 45 are correspondingly shown in FIG. 9 would result in the electric motor or prevent it from lighting up again with 22, the step contacts with 46, 47, 48 and would.

the signal lamps are designated by 43, 44 and 45. The parallel to one in the signal lamp circuit

The motor is switched by an air contactor b located measuring resistor W , a recorder S can

with the switch contacts b _v b ₂ . A main 20 can be switched with c. With the number of those that light up

switch and d designates a command switch. Signal lamps 43 to 45 fluctuates the voltage in the

On the camshaft 21 sits a line n as a second cam. If you look at the voltage fluctuation on

Control cam 49, which receives a relay switch e affecting resistance W over time

flows. The switch d is used to provide information about the number of

clock d _x and with the switch e a safety-compliant time period and tests carried out

bar ^ ₁ together. In the circuit of the signal lamps about the quality values or quality values

43 to 45 are the relays /, g, h with the holding groups. It gives you some control over

clock f _v g _v A ₁ and the switch contacts / ₂ , g ₂ and A ₂ . the regularity and conscientiousness of the

With i a control transformer is designated, its secondary carried out samples and about the quality of the

voltage depending on the existing relay any 30 mixtures in the rolling sandboxes, what

can be chosen. The mode of operation of the elec- in turn draws conclusions on the processing of the

trical device is the following: After the closing molding sand admits.

The main switch c, which connects the device to the assumption that the molding shop holds the molding sand network, is activated by actuating the command switch with which test rods 5 are only produced with a flexural strength of less than 60Kp / cm ^{2, which are only designed as push-button switches} d the contactor b energizes, which they leave, for useless. She also wants both contacts O ₁ and b _{2 to} close. This is used to deliver which molding sand mixes test bars 5, the contact b _{2 of} the motor 22 is switched on. Immediately with 60 to 75, 75 to 90 and over 90 Kp / cm ² bendable on it, about half a second later, results in strength. Accordingly, the control cam 49 is the relay switch e, whereupon 40 device calibrate in such a way that when testing the command switch d would be released again 5 below 60 Kp / cm ^2, the display of the device can, since the relay b via the current path of the switch - does not respond. So none of the step contacts 46 ters e remains energized. through 48 (FIG. 1) closes, and none of the lamps 43

Lies on the supports 4 of the device until 45 lights up. With a flexural strength of the

according to FIG. 1 no test bar 5 or is its strength 45 test bar 5 with more than 60 Kp / cm ² closes the step

The speed is so low that it breaks before the contact 46 and the lamp 43 lights up. At over

The first step contact 46 closes, the signal remains 75 Kp / cm ² , the step contact 47 closes, and the

lamps 43 to 45 dark. After a full um- lamp 44 lights up next to lamp 43. At over

Rotation of the cam 49, the switch e is opened. 90 Kp / cm ² closes the step contact 48, and all

The contacts O ₁ and b ₂ drop out. The motor 22 50 three lamps 43, 44 and 45 light up.

stops and the device can start again. The adjustment of the step contacts 46 to 48 to

will be started. certain core strengths are carried out as follows-

If there is a test bar 5 with such a strength men: On the support brackets 4, instead of one that closes the first step sand sample, a flat sample of spring steel is placed, contacts46, then the 55 on the underside is made through this a strain gauge relay / energized, which is provided with its normally open contacts f _t and f ₂ . From the strain display one with the concludes with the result that the signal lamp 43 connected to the strain gauge is illuminated at the time. If the test rod 5 breaks, at which point of the lighting up of the signal lamps 43, 44 and the relaxing spring 15 pushes the shaft slide 10 45 the corresponding spring force again so far away from the drive slide 17, 60 NEN. The step contacts 46, 47 and 48 are so that the step contact 46 opens again, this remains adjusted until the lighting of the relay / energized via the holding contact J ₁ , and the desired force values occur.
Signal lamp 43 remains on. It is only discharged Optionally one may, such as the schematic albeit showing two by again actuating the Kommandoschal- representation according to Fig. 10, next to tersd, for example for introducing a new Prüfvorgan- 65 or successively arranged printing stamp according ges, the break contact d _± power to the relay / F i g. Provide 1 in a common housing interrupts, whereupon its working contacts Z ₁ and / ₂ and a common shaft part 18 α drop. drive.

Claims (16)

Patent claims: 1. Flexural strength tester for foundry core sand mixtures, in which a test rod made from the mixture to be examined and having a square or prismatic cross-section on two rounded support cutting edges arranged at a certain distance from one another placed and in the middle between the cutting edges by a on a measured value display acting movable pressure cutting edge is loaded, characterized by the partial Characteristics known individually or in combination with one another, a) that between an upper (17) and a lower slide (10) an axially acting calibrated spring member (15) is provided, b) that the upper slide (17) by an electrically driven cam (20) or a positive cam control (37) with as linear a control as possible in the area of the test pressure Thrust cam is driven, c) that the drive is assigned an electrical relay circuit (Fig. 9), which maintains this after switching on until the aforementioned cam (20) or another cam (49) that is also driven switches the drive motor (22) off again, d) that the lower slide (10) driven by the spring member (15) holds a pressure shaft (7) which carries the pressure cutting edge (6, 6 a) on its end face, e) that on the pressure shaft (7) a number of lower or lower in its direction of movement one behind the other step contacts (46, 47, 48) for a display (43, 44, 45) certain Flexural strength value groups are arranged and f) that the two carriages (10, 17) by means of profile rollers (8, 16) along vertical columns (9) to run. 2. Apparatus according to claim 1, characterized in that the vertical columns (9) with a upper (11) and a lower plate (12) are combined to form a rigid frame. 3. Apparatus according to claim 2, characterized in that the upper frame plate (11) with a recess (19) is provided through which a from the drive carriage (17) protruding upwards Shaft part (18) up to the cam (20) of the drive motor also carried by the plate (11) (22) protrudes. 4. Apparatus according to claim 2 or 3, characterized in that the lower frame plate (12) provided with a central guide hole (13) for the pressure shaft (7) and the guide hole (13) on the underside of the plate through a elastic sleeve (14) fastened on the one hand to the shaft (7) and on the other hand to the plate (12) is sealed dust-tight. 5. Apparatus according to any one of claims 2 to 4, characterized in that in the presence a simple cam drive a return spring between the drive carriage (17) and the rigid frame is provided. 6. Device according to one of claims 2 to 4, characterized in that when there is a positive cam control (37) the the upper frame plate (11) penetrating drive shaft (18) in an eye (39) for the Engagement of the drive cam (20) ends. 7. Apparatus according to any one of claims 1 to 6, characterized in that the return of the shaft slide (10) via a screw shaft (23), which at its lower end with preferably an elastic stop (24) for the shaft slide (10) is provided, this is freely penetrated and screwed into a threaded hole (26) in the drive slide (17). 8. Apparatus according to claim 7, characterized in that the screw shaft (23) is arbitrary can be screwed deep into the threaded hole (26) in the drive carriage (17), so that with its help the Distance between the two carriages (10, 17) and thus the preload between them arranged measuring spring (15) can be adjusted. 9. Apparatus according to any one of claims 1 to 8, characterized in that the test rod support blocks (4) on one arranged at some distance below the lower frame plate (12) Base plate (1) stand and behind their horizontally lying cutting (2) with a rear stop (3) for the test rod (5) are provided. 10. Apparatus according to any one of claims 1 to 9, characterized in that a fine-thread pin (31) is screwed adjustable in its height into an end bore of the shaft slide (10) and that the plug-in part (6 a) formed pressure cutting edge (6) in a Front bore (32) of the pin (31) can be fixed in any height position parallel to the support brackets (4) with the aid of a grub screw (33). 11. Apparatus according to claim 9 or 10, characterized in that the device described above is arranged in a housing (41) enclosing them dust-tight on all sides, the only on its front side in front of the support blocks (4) through one of the base plate (1) to the lower one Has frame plate (12) reaching recess (42). 12. Device according to one of claims 9 to 11, characterized in that the base plate (1) is provided with a discharge opening for the test rod fragments, to which, if necessary connects a line leading to a collecting tank. 13. Apparatus according to any one of claims 1 to 12, characterized in that the two Carriage (10, 17) matched step contacts (46, 47, 48) are arranged, which corresponding to the resulting groups of measured values for which they are designed Switch on the number of signal lamps (43, 44, 45). 14. Apparatus according to claim 13, characterized in that the signal lamps (43, 44, 45) on the front of the device above the test rod supports (4) that make accessible Housing recess (42) are arranged. 15. Apparatus according to claim 13 or 14, characterized by a parallel to a resistor (W) in the output line (s) of the signal lamp 109 549/96 circuit (Fig. 9) switched writing implement (S), which also records the voltage fluctuations caused by the different number of flashing signal lamps (43, 44, 45) as a measured value group display on a writing pad provided with a time stamp and measured value group division. 10 16. Device according to one of claims 1 to 15, characterized by a double arrangement of two pressure shafts (6, 7, 10, 15, 17) side by side or one behind the other with their associated Support brackets (4) under a common drive (20, 21, 22 or 49) in one common housing (41). 1 sheet of drawings