MACHINERY.

Southland Times, Issue 1259, 31 May 1870, Page 3

MACHINERY.

The machines used in the Province of Auckland for manufacturing flax are* of three kinds, made respectively by Messrs Fraser and Tinne of the Phoenix foundry, Auckland, by Messrs A. G-. Price of Onehunga, and by Messrs E. Gibbons - and Co. of Onehunga. All of these machines are, however, . identical in principle, and vary only in details by which the principle is carried out. This principle is, that the flax leaf is held between horizontal feed-iollere, revolving at certain speed, while as the leaf passes out; from them, a drum armed in its circumference with iron beaters, and revolving more rapidly than the feed-rollers, strips the epidermis and tissue away from the fibre ; means being provided for adjusting the beating drum toa -proper distance from the roller or bar against which the flax leaf is stripped, so that the leaf may neither on the one hand pass through without being crushed, nor on the other, have the fibres cut. Another contrivance, common to all the machines is vulcanized India-rubber; cushions, or spiral springs placed over the journals of the upper feed roller, so as'to allow different thicknesses of leaf to be passed through. The first essential of a flax machine is, of course, the quality of the fibre it produceß. This depends to a certain extent upon the shape and velocity of the beaters, but more particularly upon the ease and accuracy with which the machine can be kept in adjustment. The length of that portion of the tip of the leaf, which is left undressed by the machine, depends upon the firmness with which the feedrollers grip the thin point of the leaf, and the distance of the place where the leaf is crushed from the place where it is held by the rollers. "We know that on the one hand simple percussion with a hammer on a block of wood, and on the other Bcraping with a knife or shell, can each be made to yield good fibre, so that the limits of the speed at which the beaters strike the leaf, which is necessary for making good fibre, are probably very wide. The velocity with which the beater scrapes the flax, is, of course, the difference of velocity between the beater and the leaf as it passes through the rollers, and as the blow is delivered not at right angles to the leaf, but at; first at an acute angle, which rapidly changes to the same direction as the leaf as % the beater passes round with the circumference of the drum, it follows thati the greater the velocity of the beaters the more will their action be one of scraping and the smaller the velocity, the more wil their action be one of percussion, or Jnore properly detrussion. " In Eraser's old machine, and in Price't smaller one, the beating dram is thirtee'r

inches m diameter, armed with tourteen beaters ; consequently, when making 1260 revolutions a minute, the velocity of the beaters is 71.5 feet per second. Tbe velocity of the circumference of the feedrollers, or, in other words, 'thVvefocity of the leaf, is about 3. 7 feet per second, thus leaving a velocity of 67.8 feet per second, with which the beaters pas'* the leaf. la Gibbon's machine, the beating, drum is seventeen inches in diameter,, armed with thirty-eight beaters, and revolves at only ..half the speed of lha.t_of^JPrice'a aid Fraser's smaller machines, the feed-rollera of all moving with the same angular velocity. Consequently, when Gibboa's drum is making 680 revolutions per minute, the beatera have a velocity of 46.7 feet per Becond. The feed-rollers of this machine being slightly larger than the^others. thesfeloeity is 2.8 feet per second, making a velocity of 43.9 feet per second, with which the ! beaters outstrip the' leaf.! 180 that the velocity of the beaters to the feed is as*l r 17 in Gibbon's, and as 1 : 26 in Price's and Fraser's old machines. _In JPrice'a and Fra^er's-old machines there are fourteen beaters .on each drum, the feedrollers are 2.5 inches in diameter, and the drum makes five revolutions to one of the feed-rollers, so that each blow of a beater jia, on* an average (as 'thej beaterarare not equi-distant), rather more than one-ninth of an inch from the one before it. la Gibbon's? drum there are>! thirfiyneight beaters, the feed-rollers are 2.6 inches in diameter, and the drum makes 2£ revolutions .to one of the feed rollers. Consequently, each blow is delivered rather more than, one-twelfth of an.inchjbehmd the former one, and the power saved is proportionately great. .••-<_-■•.>• _ Notwithstanding these -differences in velocity and in number of blows to an inch, we areof opinion, that-all the machines when in ■ proper adjustment, make equally good flax. In Price's and Fraser's old machines the beaters were placed diagonally across the face of the drum, sloping alternately in opposite directions, and the spaces between them were filled with wood. Gibbon's new machine has the beaters set on the- angle, but all running parallel, which + - allows Price's new machine the drum is 15 inches in diameter, with 26 beaters^ r which are of the same kind as : in the" smaller machines, but; being placed .closer together, increase the rapidity, , of the blow. Messrs Price tried the chevroned beaters, but afterwards abandoned^ them. In all these larger drums the jwfpod be* . tween the beaters is omtiited. We are of ■opinion that the position of the beaters on the drum matters but little so ; far as making good flax ia concerned, provided that the velocity is sufficiently and .the striking edge of the beater round and smooth. It may here be remarked that Captain Hutton thinks that the beaters on the drum should f be hard ; but that the bar or plate against which -the. flax is crushed should be sort. Mr ßooth, of Dunedin, is endeavoring to carry out at least a portion qif. this idei.' v r ; .' The adjustments of the different machines vary considerably ;• but all are capable, with more; or less e'Sise, 6f; Adjustmerit while the machine is in motion ; a point of the greatest importance. In Price's machine the flax : is ' crushed between the beaters and .the lower feed roller. And in his earlier machines the distance between the two was regulated by means of screws which indyed the journals of the beating drum forwards and backwards on a sliding bed; now the drum is fixed, and the whole' of the - standards carrying the feed-rollers are moved in the same way, which? allows the feeder to adjust his own machike moving from his place. ' ; 5 ' ' ; In Fraser's new machine the flax is stripped against a thick plate rounSed at ~ the end, which is slipped under, fher feedrollers ; the back of the plate has a flange, which is pressed forward by two. screws against India-rubber, the elasticity of which pushes the plate back: when the screws are loosened. This adjustment is very easily made by the feeder. In Gibbons's machine a round bar. with square ends takes the place of the, -plate, and being near thebeating drum* it leaves very little of the leaf undressed. The adjustment is given by pinching-screws, which act through the boxes carrying the journals of the beaters. ,— The wear upon both the surfaces of metal, between which the flax is dressed, is very great, while the slight wear prevents the machine from dressing the flax properly, so that the surfaces have to be constantly filled up or changed. In. Price's machines, the lower roller, vagaint which the flax is dressed, is a cast-iron; hollow cylinder. As their roller is three inches in diameter, and by constantly ; revolving always presents different surfaces to the beaters, it lasts much longer .than any other of the machines ; but when ifc>is too much worn the machine has tobe stopped, taken to pieces, and the old cylinder ground up, which is a work of ; considerable time, but they give ...a .spare .roller with each machine. — In Gibbons's machine . the ground bar, having four-sided -ends, can be shifted so as to show four different i surfaces to the beaters as one after the other is worn out, it is then thrown away and a'new,one put in. It was at first thought "that, eight i changes might be got from each,; bar, by shifting it end for: end ;: but this is not ? the case if good flax is desired; and as the cost of the bar is trifling; tfiere 'is no i necessity for trying it. This can easily [' be done while the machine i is in^ motion. ; As Gibbons has two machines on one t shaft, the stoppage of one necessitates the s stoppage of .the other. ! K Fraser's . machine* no ■ change ; of* face can be > obtained, but. the worn plate can be > slipped out, and another put in in-a few ; seconds, without stopping the machine. 1 And the old plate can be ground up again, j ready to replace the second when it is in its turn worn follow. : The cost = of . \ these i plates is also email, being only 2s 6d each. I (Tp be continued.) ..^