United States Patent Strydom 1 NON-DESTRUCTIVE HARDNESS,

TESTING OF ARTICLES SUCH AS CIGARETTES [72] Inventor: Mauritz Leon Strydom, Stellenbosch.

South Africa [73] Assignee: Tobacco Research and Development Institute Limited 22] Filed: May 14, 1970 [2]] Appl.No.: 37,272

[30] Foreign Application Priority Data Oct. I5, 1969 South Africa ..69/72$9 May 16, 1969 South Africa. ..69/3457 [52] U.S. Cl ..73/78, 73/37.5, 73/38 [51] lnLCl ..G0ln 3/10,G0lb 13/08 [58] FieldoiSenrch ..73/78, 37.5, 37.8, 37.9, 94, 73/38 [l5] 3,668,928 51 June 13, 1972 i References Cited UNITED STATES PATENTS 2,976,7l8 3/196] Baker ..73/37.$ 3,115,772 I2 963 O'Keefe et a]. ...73/78 X 3,438,250 4/]969 Boutron r ..73/94 3,559,466 2/197] Calleson ..73/94 X Primary xaminerRichard C. Oueisser Assistant Emminer-Ellis J. Koch Attorney-Waters, Roditi, Schwartz & Nissen ABSTRACT A cigarette is tested for hardness by inserting it into a rubber sleeve which is surrounded by rings. Air is passed through the annuli formed between the cigarette and the rings. The pressure drop is measured firstly with the cigarette interior as is, secondly with the cigarette interior subjection to a first suction and thirdly with the interior subjected to a second suction. The pressure drops are measures of the diameters of the cigarette at the various interior loadings. From these diameters and the loadings the hardness of the cigarettes may be computed.

6 Claims, 1 Drawing Figure PAIENTEum 13 m2 NON-DESTRUCTIVE HARDNESS. TESTING OF ARTICLES SUCH AS CIGARETTE This invention relates to the non-destructive hardness testing of articles such as cigarettes.

Conventional hardnes testers measure the depth to which a plunger acting under a predetermined force dents the periphery of a cigarette. The depth of the dent is some inverse function of the true hardness expressed in gin/mm. instrw ments which are able to give a reliable measure of the hardness of cigarettes by the conventional method are highly sophisticated and therefore expensive. A method of making and measuring dens caused by gas flow is described in U.S. Pat. No. 3,411,5l3.

In U.S. Pat. No. 3,1l5,772 it has been proposed to insert a cigarette into a sleeve, to apply pressure by liquid means to the sleeve and to measure the volume of gas expelled from the cigarette. The ratio of the volume before compression and the volume after compression is said to be a measure of the "firmness" of the cigarette. The term firmness as used in the U.S. specification and the term "hardness" used in this specification are interchangeable.

The applicant now proposes a method and apparatus which does not rely on liquid pressure or on the measurement of a small volume of gas expelled from a cigarette.

A method according to the invention comprises applying a first pressure to the outer covering and recording that pres sure; establishing and recording the diameter of the article at the first pressure as a first diameter; pneumatically compressing the article at a second pressure higher than the first pressure and recording the second pressure;

establishing and recording the diameter of the article at the second pressure as a second diameter; and

deriving a measure of a property of the article from the diameters and pressures thus recorded.

The invention is further discussed with reference to the accompanying drawing which is a schematic representation of apparatus suitable for carrying out the method of the inven tion with the main component in section.

The heart of the unit consists of a series of rings 4 adapted to surround a cigarette 3. Alternate sides of the rings 4 are connected to a chamber 2 and to a chamber 25 which is at atmospheric pressure through a port 26. The cigarette is held in position by means of a thin rubber tube 24 which is stretched to such an extent that its inside diameter is smaller than that of the cigarette 3.

A plug 5 seals the cigarette 3 from atmosphere and at the other side a tube 6 connects the inside of the cigarette 3 to a suction system.

The chamber 2 is connected to a vacuum pump 12 through a critical flow orifice l0 and a shut-off valve 11. The vacuum pump 12 provides suction of at least 0.6 Kp/cm.

A transducer 7 measures pressure in the chamber 2 which is a function of the diameter of the cigarette 3. A transducer 8 measures the suction applied to the cigarette. Transducers 7 and 8 can be sampled by a scanner/digital voltmeter 9.

As a result of the inclusion of the critical flow orifice 10 in the circuit the rate of flow from the chamber 2 remains constant within wide limits regardless of the diameter of the tube 24 as long as there is clearance between the tube 24 and the rings 4.

it is well known to measure the diameter of an article by measuring the pressure drop in a gas flowing through an annulus formed aroung the article. in the present case each of the rings 4 forms such an annulus. Since there are several rings 4 (four in the illustrated embodiment) the pressure reading in the chamber 2 is a measure of the diameter of the tube 24 as averaged over those several diameters that are surrounded by the rings 4.

Shut-oil valves 14 and 15 connect the cigarette interior to suction chambers and 21. Suction in chambers 20 and 21 is maintained at approximately -0.l and 0.4 Kp/cm respectively by means of control valves 17 and l8.

'lheport26maybeclosedbymeansofavalve27actuated byapneumatlc cylinder-23fedwithcornpreaedairthrough valve22. Openingofthe valve 22cauaed the valve 27 locloee the port26. Closingofthe valve22allowstheport26toopen Ashut-oflvalve 13 controls theadmhaion ofsuction to the chamber 25. The-valve 13 leads to a suction chamber 19 the pressure of which is conu'olled by a valve 16. 'lhe pressure in thechamber Uissoregulatedthatwiththeportficloeedthe tube 24 is caused to stretch to a sufficient extent to allow for the insertion of a cigarette.

The test sequence is as follows:

Assume all shut-off valves closed. Open the valve 22. The cyIinderBisactivatedbycompressedairandthe port26is closed. Open the valve 13. The rubber tube 24 is expanded. lnsertacigarette,theplug5a.nd the tube6. Close Hand 22 sothattheport26isagainuncovered. lfthe valve ll is opened, the unloaded diameter DU can be obtained from the readingofthetransducerlonthe voltmeter! Openingthe valve 14 will cause a pressure load. of 0.1 Kp/cm' on the cigarette. The transducer 7 reads D1 and the transducer 8 reads Pl. likewise D2 and P2 are obtainable by closing the valve 14 and opening the valve 15.

Closing the valves 15 and 11 and opening the valves 22 and 13 will again open the tube 24, preparatory to replacing the cigarette with the next to be tested.

Note that D! and D2 are taken at pressure above a PO which is equal to the pressure exerted by the tobacco on the paper wall.

After correcting D1 and D2 by subtracting the thickness of the tube 24, hardnessll-P may be computed by utilising the formula:

H (P2-Pl) DU/ (DlD2) gin/mmwhere DU is the unloaded diameter P1 is the pressure of first loading P2 is the pressure of second loading D1 is the diameter under loading of?! D2 is the diameter under loading of P2 The pressure initially exerted by the tobacco on the paper wall may be computed as The hardness figure computed from measurements taken in the manner described above according to the above formula conforms very closely to figures determined by more conventional ways. In addition the figure of pressure exerted by the tobacco is very useful for comparison purposes during the control of cigarette manufacture.

Note that the tube 24 is not essential for a measure of hardness to be obtained. However, if the tube 24 be not used, the porodty of the cigarette paper will afl'ect the measurements and these will have to be adjusted accordingly. In view of the absence of these adjustments when a tube is used, it is preferred to use the apparatus with the tube 24.

I claim 1. Apparatus for testing a cylindrical article such as a cigarette comprising a filling material and an outer covering, comprising:

means for supporting the article;

means for fluid-tightly sealing olf one end of the article;

meam for applying suction to the outer end of the article;

a chamber surrounding the article and at least one ring the chamber dividing the chamber into two compartments, the ring surrounding the article with an annular gap between it and the article;

meam for causing gas to flow through the annular gap from one side of the ring to the other side of the ring;

meam for measuring the pressure difierence between both sides of the ring; and

means for measuring the suction applied to the other end of the article.

2. The apparatus claimed in claim 1 including a gee-imperviour sheath for clrcumferentlally enclosing the article the gap being between the ring and the sheath.

3. The apparatus claimed in claim 2 in which the sheath is held in the chamber and including means to clone the chamber 5 and means to apply auction to the chamber to allow the sheath to expand to accept an article.

4. The apparatus claimed in claim 1 in which there are a plurality of rings arranged so that in the case of each ring, gas flow is from a first space to a second enclosed space, the first space being open to atmosphere and including means for subjecting the second space to suction.

5. The apparatus claimed in claim 4 in which the second space is connected to the means for subjecting it to suction 6. Apparatus for testing a cylindrical article such as a cigarette comprising a filling material and an outer covering,

comprising a chamber having two end walls connected by side walls an opening in the side walls a shut off valve for controlling the opening regiltering borer in the end walls means for applying suction to the first space in the chamber; Mr M 7 W m. means for applying suction to the second space in the chamber; a critical flow orifice connected between the latter suction means and the second space meansformeasuringthepressureinthesecondapacemnd means for measuring the suction applied to the other end of the tube.

i t i 4 Q