US2656712A - Dilatometer - Google Patents

Description

1953' i G. E. COMSTOCK 3RD DILATOMETER Filed April 18 1949 3 Shee'tS-Sheet 1 lzvvewme Oct. 27, 71953 G. E. COMSTOCK 3RD 2,656,712

DILATOMETER Filed April 19, 1949 3 Sheets-Sheet 2 luvzurm? 650/265 5 (oMsrarK 1 HTTQRNE' Y Patented Oct. 27, 1953 DILATOMETER George E. Comstock 36,. Worcester, Mass., as-

signor to Norton Company, Worcester, Mass., a corporation of Massachusetts Application April 19, 1949, Serial No. 88,457

16 Claims.

The invention relates to dilatometers.

One object of the invention is to provide a highly accurate dilatometer. Another object of the invention is to eliminate errors due to expansion and contraction of the parts of the dilatometer. Another object of the invention is to provide a dilatometer of simple construction and low cost which nevertheless is very accurate.

Another object of the invention is to provide a dilatometer which can be quickly set up. Another object is to provide a dilatometer with which may be made accurate calculations of thermal coefficients of expansion over a wide range of temperatures. Another object is to provide a dilatometer which is rugged and dependable in operation.

Other objects will be in part obvious or in part pointed out hereinafter.

The invention accordingly consists in the features of construction, combinations of elements and arrangements of parts, all as .will be illustratively described herein and the scope of the application of which will be indicated in the following claims.

In the accompanying drawings illustrating one of many possible embodiments of the mechanical features of this invention,

Figure 1 is a front elevation of a dilatometer constructed in accordance with this invention, with parts of the movable half of the casing cut away to show the interior and showing the transformer construction in vertical section.

Figure 2 is a side elevation of the dilatometer.

Figure 3 is a horizontal sectional view of the casing taken on the line 3-3 of Figure 5.

Figure 4 is a side elevation of the dilatometer.

Figure 5 is a vertical sectional view of the easing taken on the line 5-5 of Figure 1.

Figure 6 is a side elevation of one of the heating coils.

Figure '7 is an end elevation of the heating coil of Figure 6.

Figure 8 is a wiring diagram illustrating the wiring of the transformer.

Referring first to Figures 1, 2 and 4, for the support of the dilatometer I preferably provide three supports each comprising an iron base plate I!) supporting a pair of L-irons II to which are cemented flexible rubber pads l2 which in turn are cemented to the sides of an inverted channel iron IS.

The dilatometer has an iron base plate into threaded holes of which extend three round nose screws Hi to which are secured knurled wheels II. The screws I6 are placed on the inverted channel irons I3 and then by turning the knurled wheels ll the base plate l5 can be leveled. Vibrations of all sorts in the building where the dilatometer is located are considerably deadened by the rubber pads l2. It is important that the dilatometer should be just as steady as possible but it may be desired to use it in a factory building where heavy machinery vibrates the building or near a railroad track where each passing train vibrates the earth for a considerable distance from the track. This mounting permits the dilatometer to give accurate results even in such 10- cations.

Secured to the topof the base plate [5 as by means of bolts 19 is an angle iron bracket 20 and secured to the side of the angle iron bracket 20 as by means of screws 2| is the rear half 22 of a casing the front half 23 of which is movable. The casing 22, 23 is shown as a hollow rectangular parallelepiped and may be made of sheet steel. This casing 22, 23 is shown in Fig ures l, 2, 3, 4 and 5. As shown in Figure 4, a hinge plate 24 is secured by screws 25 to the stationary rear half 22 and a hinge plate 26 is secured by screws 21 to the front half 23 while a hinge pin 28 connects these hinge plates 24 and 2B. As shown in Figure 2 a hinge bracket 29 having spaced portions 30 is secured by screws 3| to the casing half 22 and a hinge pin 32 passes through the enlarged flattened end 33 of a rod 34 having a threaded end 35 receiving a nut 36, spring 31 and washer 38 and the rod 34 can be swung to extend into the slotted end 39 of an angle iron bracket 40 secured as by welding to the front half 23 of the casing. By swinging the rod 34 outwardly and to the right as shown in Figure l, the front half 23 is released from the rear half 22 and thereupon the front half 23 can be pulled open to any extent up to and even beyond 90.

Referring now to Figures 6 and '7, the heating elements for the dilatometer may comprise coils wound on hemicylindrical shells 46 of insulating and refractory material. Conveniently the coils 45 maybe wound as shown, that is to say running approximately along cylindrical elements of the shells 46.

Referring now to Figures 3 and 5, one hemicylindrical shell 46 is located in the rear half 22 of the casing while the other hemicylindrical shell 46 is mounted in the front half 23 of the casing. through holes 48 in the ends of the casing halves 22 and 23 and are secured to binding posts 49 The ends 41 of the coils 45 extend,

which are connected to binding posts 50, these binding posts 49 and 50 being mounted on insulating panels 5| secured by screws 52 to the casing halves 22 and 23 all as shown in Figure 4. The binding posts should be connected to electrical energy to heat the coils 45 to attain the desired temperature inside of the casing 22, 23.

Referring now to Figure 3, metal walls are secured as by welding to the inside of the half 22 and similar metal walls 56 are secured as by welding to the inside of the half 23. These walls 55 and 56 extend parallel to the ends of the halves 22 and 23. In the half 22 between the walls 55 is a refractory block 51 while in the half 23 between the walls 56 is a refractory block 58. Just outside of the walls 55 are refractory pieces 59 and just outside of the walls 56 are refractory pieces 60. The blocks 51 and 58 are grooved to receive the coils 45 and the shells 46 as indicated in Figure 3 and in front of the coils 45 and shells 46 are placed long hemicylindrical refractory shells 65 which are held in position by screws 66 that pass through the shells 65 and are screwed into the pieces 59 and 60 and which also extend through metal bars 61 which clamp the ends of the shells 65. The foregoing provides a refractory heat insulating structure supporting the coils 45 in position to heat the cylindrical compartment I0 inside of the shells 66 which compartment I0 is substantially closed when the casing is closed. The ends of the compartment '10 are blocked by cylindrical blocks II made of refractory material and cemented to the shell in the casing half 22.

Outside of the refractory pieces 59 and 60 in the casing halves 22 and 23 respectively are additional refractory blocks I2 and 13 respectively, the former of which may have projections 14 fitting in depressions I5 in the latter. These as well as the blocks 'Il constitute baiiles to eliminate or reduce any transfer of heat by convection flow of air. Additional baflles may be provided, and referring to Figure 5 the block 58 may have an upper projection I6 and a lower projection H which respectively fit in depressions I8 and I9 in the block 51 when the casing is closed.

Extending through the casing half 22, through a block I2 and through a block II is a refractory rod having two bores (only one of which is shown) through which extend the two sides of a thermocouple wire 8| whereby the temperature of the compartment I0 may be measured at any time.

Referring now to Figures 1, 2 and 4., secured to the base I5 by means of nuts on threaded ends 86 are a pair of rods 81 which extend upwardly from the base I5 and have secured to the tops thereof a cross-piece 68 by means of nuts 89 on threaded ends 90 of the rods 8'1. Secured to the cross-piece 88 in similar fashion (not shown) are a pair of parallel inclined rods to which is fastened, by means of nuts 96 on threaded ends 91, a cross-bar 98 having a front vertical face 99. A pin I00 projects forwardly from the face 99 and thereon is a ball bearing [0! (Figure 1) journalling a head I02 on the end of a lever rod I03. A block I04 is drilled at each end and has a rectangular opening I05 therethrough extending from side to side of the block. The lever rod I03 extends into one end of the block I04 and is secured thereto as by means of a screw I06.

Into the other end of'the block I04 extends a lever rod I01 which is secured in place by a screw I08. The bottom of the rod I0! is threaded, drilled and split and thereon is screwed a chuck I I 0. A supporting rod I I I has a reduced diameter upper end which fits in the fine bore in the lower end of the rod I0? and is gripped when the chuck I I0 is tightened. This rod I I I can be made from a plain piece of wire and is bent into a shape like a question mark as shown in Figure 5. The chuck I I0 is a hollow body with a screw threaded bore the bottom of which is tapered inwardly. The supporting rod III can readily be removed from the lever rod I01 by opening the chuck I I0.

In similar fashion a supporting rod II2 which may be exactly like the supporting rod I I I is fastened by a chuck H3 to a rod II4. I provide an integral piece of steel II5 which is rectangular in cross section and has a pair of parallel portions II6, I I! which are perpendicular to the upper part of the piece I I5 and are connected by an offset portion I I8. The bottom part of the piece H5 is drilled and receives the rod II4 which is secured in place by means of a screw I20. A metal sleeve I2I is received between the parallel portions I I6 and I I! and is secured thereto as by welding. The integral piece of steel I I5 is secured to the front vertical face 99 of the cross bar 98 as by means of a screw bolt I23 and a pin I24.

Comparing now Figures 1 and 2 and referring first to Figure 2, a bar I25 is secured by screws to the offset portion H9. This bar I25 has been removed in Figure 1 so as to show a, ball bearing roller I26 mounted on a pin I21 which extends through the bar I25 and also through the offset portion II 8. Resting on the ball bearing roller I26 is a rod I30 having an enlarged end I3I containing a ball bearing I32 which is supported by a pin I33 extending from side to side of the block I04 through the rectangular opening I05. Mounted on the rod I30 is a tubular piece of iron or other magnetically permeable material I34. This piece of iron I34 is a core for the transformer I35 and since it is the movement of the core I34 which causes the readings, the rod I30 on which it is mounted is best made of non-magnetic material, for example a non-ferrous metal other than cobalt or nickel.

Held in place by the metal sleeve I2I around the tubular piece of iron I34 is a transformer I35. This transformer I35 comprises a hollow cylinder I36 of insulating material wound with three coils I31, I38 and I39. Referring now to Figure 8, the coil I38 is the primary coil and its ends I40 and MI are connected to high frequency alternating current power for example at an electromotive force of 6 volts and a frequency of one kilocycle. The coil I3! is a secondary coil and one end is connected by a wire I42 to an instrument I43 which may be considered to be a voltmeter and may be any sensitive instrument to measure and preferably to record the E. M. F. of the secondary. This instrument I 43 may include an amplifier to enable the operator to discriminate between very small voltage differences.

The other side of the instrument I 43 is connected by a wire I44 to one end of the coil I39 which is also a secondary coil. The remaining ends of the secondary coils I31 and I39 are connected to each other by means of a wire I45.

In Figure 8 the direction in which the coils i 37 and I39 are wound is indicated, and the manner of winding together with the circuit connections are such that, with the core I34 in the center of the transformer I35, the E. M. F. of the wire I42 is the same as and of the same design as the E. M. F. of the wire I44 at any instant and therefore the instrument I 43 will register zero. However even the most minute displacement of the core I34 will unbalance the system to cause the wires I42 and I44 to be out of phase to some extent and this will cause a reading on the instrument I43. Furthermore the greater the displacement the higher will be the reading.

Referring now to Figures 1 and 5, the sup.- porting rods III and II2 extend into the casing through grooves I in the blocks 51 and 58 and in the top of each of the casing halves 22 and 23 and these grooves 150 are wide enough to permit on the one hand the rod I I2 to be free of mechanical interference, and on the other hand to permit the rod III to move. As a specimen I5I placed on the horizontal portions I52 of the supporting rods II I and I I2 is being tested, some heat escapes through these grooves I50 by convection and accordingly as shown in Figures 1, 2 and 4, I may provide water jackets I55, I56 and I5! secured as by welding to the outside of the metal sleeve I2 I. In this illustrative embodiment the water jacket I55 is nearly a quadrant and so is the water jacket I 51 while the water jacket I56 is nearly a hemicylinder. A pipe I58 connected to a hose I59 leads water to the jacket I55, a pipe I50 conveys water from the jacket I55 to the jacket I56, a pipe I6I conveys water from the jacket I56 to the jacket I51, a pipe I62 discharges water from the jacket I57 and a hose I63 on the pipe I52 takes the water away to any sump, receptacle, sink or the like. A small flow of water will suffice and the hose I59 can be connected to a bottle or a can containing the water.

To calibrate the apparatus a specimen I5I of known expansion characteristics is placed on the horizontal portions I52 with the casing open and then the current is turned on in the primary I40, I4I. This will usually give a reading on the instrument I43 but then the lever system consisting of the rods I03, I01 and III is gently moved back and forth until the reading is zero and remains zero after any vibrations have stopped. Then the casing is carefully closed and clamped tight by turning up the nut 36 and the room temperature is noted. Then the coils 45 are energized and the thermocouple wire 8| is connected to a recording instrument to record the rising temperature at every moment of time. The instrument I43 should also have a recording graph which will show the voltage at every interval of time. From the two graphs can be plotted the expansion represented by any E. M. F. The distance between the two horizontal portions I52 is of course carefully measured.

Now the entire sequence is repeated with a specimen I5I whose coefficients of expansion are to be determined.

It will be noted that expansion of the supporting rods III and II2 due to rise of temperature can have little effect upon the result for they expand at right angles to the movement of the core I34. I have also provided rods III and H2 made out of sintered alumina which has a lower coefficient of expansion than most metals and which also reduces heat flow away from the specimen l5I by conduction. Such supporting rods III and H2 made out of sintered alumina are of course quite delicate and therefore in many cases it will be preferred to use metal supporting rods.

It will be seen that due to the mounting of the lever system )3, I01, III this lever system can, when the front half 23 of the casing is opened, be swung at least 90 to withdraw the rod I30 and core I34 from the sleeve I2I to make any adjustments or repairs desired. Furthermore all parts of the dilatometer are readily accessible for the purposes of adjustment and repair. There is very little friction in the apparatus and errors due to friction are substantially non-existent.

While there is some mechanical force on the core I34 when it is away from the zero position, this is extremely minute in magnitude and has been found not to displace the movable horizontal portion I52 relative to the specimen I5I nor measurably to bend the lever system I03, Iii'i, ill. The movement is so small that this lever system is very close to vertical at all times and so its weight does not distort it. The integral piece of steel II5, the rod II4 and the supporting rod II2 are also vertical and are found to remain stationary during an instrumental operation involving heating of the specimen I5I to above 1000" C. At least it has been found that a given specimen I5I of known coefficients can be measured over and over again with the same results so therefore the instrument is deemed to be thoroughly reliable.

Another way of calibrating the instrument is to open the front half 23 of the casing and carefully set the movable part of a micrometer against the inside edge of the horizontal portion I52 of the supporting rod III. The primary I30 should now be energized and the micrometer turned while the instrument I43 is read for each increment of movement of the micrometer. The changes in electromotive force recorded by the instrument I43 are linear with respect to movement of the micrometer and therefore when a given voltage difference has been established as equivalent to a given expansion any specimen can be readily tested.

While I have mentioned an electromotive force of 6 volts and a frequency of one kilocycle, these values may be widely varied although for a given calibration the voltage across the primary should not be changed to any considerable extent nor should the frequency be changed to any great extent without recalibration.

It will thus be seen that there has been provided by this invention a dilatometer in which the various objects hereinabove set forth together with many thoroughly practical advantages are successfully achieved. As many possible embodiments may be made of the above invention and as many changes might be made in the embodiment above set forth, it is to be understood that all matter hereinbefore set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

I claim:

1. In a dilatometer, a stationary specimen support having a generally horizontal supporting portion for one end of a specimen, a member having at its lower end a generally horizontal specimen supporting portion for the other end of the specimen and which is on the horizontal level of the supporting portion of the stationary support so that the specimen can extend horizontally between said supporting portions and be supported thereby, a stationary pivotal. mounting. pivotally connecting the upper end of said member to and for turning movement about a fixedaxis located above and in a vertical plane extending through said supporting portion of said member which plane is perpendicular to the plane of displacement of said member with respect to the stationary support, means surrounding said specimen supporting portions for heating the specimen, and means responsive to 7 motion of said pivotally mounted member for measuring the displacement of the supporting portions relative to each other.

2. In a dilatometer as claimed in claim 1, the combination with the parts and features therein specified, of the further feature that the supporting portion of the movable member is on a part of said movable member having the general shape of an inverted question mark.

3. In a dilatometer as claimed in claim 1, the combination with the parts and features therein specified, of the further feature that the movable member comprises two pieces and the piece having the supporting portion is made of refractory material.

4. In a dilatometer as claimed in claim 1, the combination with the parts and features therein specified, of the further feature that the stationary support includes a substantially straight elongated vertical member having the supporting portion at its lower end.

5. In a dilatometer as claimed in claim 4, the combination with the parts and features therein specified, of the further feature that the substantially straight elongated vertical member is detachable from the remainder of the stationary support and is made of refractory material.

6. In a dilatometer, a base, a generally upright structure mounted on the base, means for suspending a specimen in substantially horizontal position from said structure including spaced supporting means depending from said structure and having substantially horizontal supporting portions at their lower ends which are located in the same horizontal plane and provide spaced cradles for the specimen, one supporting means being stationarily aff xed to the upright structure, a pivotal mounting connecting the upper end of the other supporting means to the upright structure for pivotal movement toward and away from the fixed supporting means and so that the center of gravity of the movable supporting means is substantially vertically aligned with said pivotal mounting, means for heating the specimen, and means for measuring the displacement of the supporting portions of said supporting mean relative to each other.

7. In a dilatometer as claimed in claim 6, the combination with the parts and features therein specified, of the further feature that the lower end portion including the horizontal supporting portion of at least the movable supporting means has the general shape of an inverted question mark. a

8. In a clilatometer as claimed in claim 7, the combination with the parts and features therein specified, of the further feature that at least the movable supporting means comprises two pieces and the piece having the substantially horizontal supporting portion is made of refractory material.

9. Ina dilatometer as claimed in claim 6, the combination with the parts and features therein specified, of the further feature that the supporting means each comprises two vertically aligned pieces and the piece having the substantially horizontal supporting portion is made of refractory material.

10. In a dilatometer as claimed in claim 6, the combination with the parts and features therein specified, of the further feature that the measuring means is operatively connected to the mov- 8 able supporting means intermediate the ends thereof.

11. In a dilatometer, a substantially sealed specimen heating chamber, means for supporting a specimen in horizontal position Within said chamber comprising a pair of spaced upright members depending from points of support disposed above said chamber and having lower end portions extending into said chamber, one of said members being stationary and the other being pivotally mounted from its point of support for movement toward and away from said stationary member, said lower end portions of the members having horizontal portions disposed in the same horizontal plane and providing spaced supporting cradles for the specimen, means for supplying heat to said chamber thereby to heat the specimen supported on said horizontal portions, and means responsive to movement of said pivotally mounted member for measuring the displacement of its horizontal portion occurring upon expansion of the heated specimen.

12. In a dilatometer as claimed in claim 11, the combination with the parts and features therein specified, of the further feature that the horizontal portion of the pivotally mounted member is normally disposed in vertical alignment with its pivotal point of support.

13. In a dilatcmeter as claimed in claim 11, the combination with the parts and features therein specified, of the further feature that at least the lower end portions of said members are made of a similar refractory material.

14. In the dilatometer as claimed in claim 11, the combination with the parts and features therein specified, of the further feature that said members are of sectional construction and the lower sections which include said lower end portions of said members are detachable from the upper sections thereof.

15. In a dilatometer as claimed in claim 11, the combination with the parts and features therein specified, of the further feature that said horizontal portions and adjacent lower end portions of said members have the general shape of an inverted question mark.

16. In a dilatometer as claimed in claim 11, the combination with the parts and features therein specified, cf the further feature that said measuring means is supported externally of said heating chamber by said members and substantially in the space between said members.

GEORGE E. CO'MSTOCK 31).

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 941,359 Cowen Nov. 30, 1909 2,026,299 Boyd Dec. 31, 1935 2,180,175 Sivertsen Nov. 14, 1939 2,380,565 Wetherbee July 31, 1945 2,427,866 Macgeorge Sept. 23, 1947 FOREIGN PATENTS Number Country Date 513,383 Germany Nov. 25, 1930 OTHER REFERENCES An article entitled An Electromagnetic Indicating or Recording Remote-Reading Rotameter by Clark in a Journal of Scientific Instruments and Physics in Industry, vol. 25, No. 8, Aug. 1948, pages 257-262.

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