US1513093A - Microtome - Google Patents

Description

M. T. DENNE M'ICROTOME Filed Oct. 19, 1920 3 Sheets-Sheet 1 //VVf/V7fl/? MarK Thomas Denna Patented Get. 28, 1924.

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MIGROTOME.

Application filed Getober 19, 1920. Serial No; 418,666.

To (all. whom it may concern:

Be it known that 1, MARK THOMAS DENNE, a subject of the King of Great Britain, residing at Edgehill, lVarlingham, in the county of Surrey, England, have invented a new and useful Improvement in Microtomes, of which the following is a specification.

This invention has reference to improvements in and relating to microtomes, and in particular to that type of such machine in which the subject or mass to be cut into extremely thin sections for anatomical and biological purposes and the like, is reciprocated in the vertical plane relatively to a stationary knife.

i'ilthough machines of the aforesaid type are generally preferred, they are not by any means satisfactory as heretofore constructed, notwithstanding that those engaged in designing such machines are well aware of the difficulties of the problem and which will be at once apparent if one contemplates that the subject or mass has frequently to be cut. into sections of .001 mm. thickness.

As result of a good many experiments and careful tests I find that when using machines of the aforesaid type there is at times a considerable variation in the thicknessof'the sections cut, not only when different-sections out are compared but even in the thickness of'di-fferent portions of each individual section (of course the term con siderable has to be construed in the light of the extremely fine measurements that have to be made).

This want of regularity is, I find due to various causes. Firstly the mass to be sectioned is carried in a holder that is mounted on a slide or carriage which is made to travel in the horizontal direction to feed the mass relatively to a. stationary knife, the

carriage being in turn supported by a vertical' slide which is made to reciprocate on a post. By reason of there thus being two slid s, the work holder overhangs or projects away from the rigid post a considerable distance and this itself producesa want;

of rigidity that seriously affects the quality of the work performed. Further as the carriage carrying the work or mass holder is constantly (intermittently) being fed forward, the overhang increases, thus increasing, to the extent of the increase in the overhang, the want of rigidity; Further, also, the micrometer feed device is also being removed.

carried by the vertically reciprocating slide to impart intermittent feed movement to the horizontal work clamp-carrying slide, thus increasing the weight or mass to be reciprocated which also serves to disturb the evenness of balancein the moving parts.

Whilst the aforesaid defects might be of no real niomentin many classes of machines, when they exist in microtomes they become very serious owing to the extreme thinness of the sections to be out.

Another defect l find is that it is almost impossible in the machines in use,to effect that precise and accurate adjustment of the.

angle of the knife which, I find, is absolutely necessary if satisfactory cutting of different subjects and varying thicknesses of sections are to be cut.

The object of my invention is to obviate the aforementioned defects, my invention comprising, further, certain useful improvements in details of the machine.

To these ends my invention consists in a microtome having in combination a vertical post projecting from the base of the machine, work clamp-carrying slide to be reciprocated thereon, a micrometer. feed carriedby the base anda knife moved intermittently along the base.

My invention, further, comprises, as important features, an improved feed'regulating mechanism" whereby any desired thickness of sections (within the. compass of the machine) may be obtained;.and also means for enabling avery precise angular adjustment of the knife to be obtained.

I wish it to be understood that my invention is not limited in its scopewtothe particularly constructional form hereinafter described and illustratedin the accompanying drawing, altho-ughthat form initself is a valuable feature of my invention.

In the accompanying"drawings Fig. l, is a side elevation of the machine, the position of the knife and its holder being me-rely* indicated by broken'lines. Fig. 2, is a front elevation, the knife and the subject holder only the base and its slide, and with the column in section. Figs. 4, and 5, are a side elevation and sectional plan of the subject holder; and Figs. 6, and 7, are a side and front elevation, respectively, of the knife holder, the knife-being, removed. i

In saiddrawings A indicates the base of the machine which will be. made somewhat Fig. 3, is a plan view of.

heavy to ensure rigidity. Upstanding from said base is a vertical column B, of approximately triangular shape in cross-section, and having accurately machined slide-ways at its angles or corner parts. Adapted to slide on said column is acarriage comprising parts C, C, which may be adapted so as to snugly fit on the column by set screws 0, c, and by means of which any wear that takes place may be taken up.

Inorder to ensure that the part C shall at all times lit snugly yet firmly against the column, I provide an antifriction roll R that is mounted to rotate on a pin 1" projecting from an eccentric shank r, so that by rotating the latter in its bearing on the part C the roll R can be brought to bear firmly against the column B and by this the part C is drawn against the column so that there is not the least danger of any slack or looseness between'them. The shank and pin are made of suitable material so that the pin W has a certain amount of spring which will materially assist in maintaining the desired firm cont-act of the part C with the column. The shank 7* after the adjustment has been effected for the purpose stated, is clamped in position. by a set-screw 7- For imparting to the carriage the necessary vertical reciprocations, I provide a shaft S, supported in suitable bearings in the base A, on the outer end of which I provide a balanced handwheel s, if the macnine is to be hand operated, or a pulley if it is to be driven by power. On the other end of the shaft I provide a crank s the crank pin 19 of which is provided with a connecting rod 8 which latter is also pivotally connected to the carriage by a pin p.

The part C of the carriage is provided with a clamp D that carries the cylindrical stein d of a supportd which is to carry the subject holder d The latter has a fixed aw L and movable jaw e which is adjusted by a screw 6 to hold or grip the subject to be sectioned. The holder d has a segmental web 7' having a flange j" which is embraced by the suitably shaped bifurcated end of a draw-bar 7. The latter passes through an aperture in the washer f which fits in a recess on the cylindrical stem (Z, and its outer end, which is screw-threaded is provided with a nut 7. By the foregoing construction and arr ngement of the parts, by slacking the nut D so as to loosen the grip of the clamp D on the stem cl, the holder (Z can be turned around a horizontal axis, and by slacking the nut f the holder 03 can be moved or swung around a vertical axis. That is to say the holder can be adjusted so that the subject can be sectioned at any desired angle, the nuts 7 and I) being, of course, tightened up when the desired adj ustments have been made. The foregoingv forms a very rigid support and yet the ad justments as aforesaid can be easily and quickly efiected, and further, the parts can be readily dismantled as and when this is necessary. The carriage may be clamped in any position by means of the screw t acting on the shaft.

The knife, indicated at H in Fig. 1, is carried in a holder (shown in detail in Figs. 6 and 7) consisting of two cylindrical discs it, h, connected by a stem k The said discs are slotted at h to receive the ends of the knife and the latter is clamped firmly in position by setscrews such as M, Fig. 6.

The said discs are carried in bearings z, i, on a block 2' which is adjustably mounted on a micrometer slide T, being engaged in a slot 25 therein, by a T bolt 2' entered in the undercut slot in the slide and which bolt can be tightened up by screwing up the screw 2' which has a part 2' of its shank tapering and which part engages against a correspondingly shaped inclined surface or wedge in the head of the T bolt The arrangement described enables the knife and its holder to be easily removed from the slide.

One of the discs (72/) has a snug m one side of which is pressed against by a spring m, which will rotate the knife holder if the set screws are slackened, and on the opposite side is acted on by an adjusting screw wa so that by screwing the latter in or out the holder will be rotated in its bearings and thereby the angle of the knife will be regulated according to the nature or character of the subject to be sectioned. The means just described enable a very fine or precise and accurate adjustment of the angle of the knife to be effected, this being a matter of very great importance when val"- ous different materials or substances have,

from time to time, to be cut into sections as thin as.001 mm. When the desired adjustment has been eflected, the holder is clamped tight by the set screws m The micrometer slide T is made of solid construction so as to be perfectly rigid, and

it is mounted in suitable guide-ways t on the base of the machine. Said slide is movedby the micrometer screw t (Fig. 1) the nut t of which is attached to one end of the slide whilst the end of the screw abut-s on a foot t rigidly attached'to the base.

The micrometer screw is rotated by means of the large ratchet wheel L which is mounted thereon in such a manner, for example frictionally, so that by slacking back a nut Z the wheel is freed from the screw so that the latter may be rotated by merely rotating the milled head Z and thus avoiding having to rotate the large ratchet wheel as and when a rapid setting back or forward of the slide T and the knife thereon'is required. There are so many known ways in which such a connection and disconnection of the ratchet wheel and its micrometer screw can be effected that detailed description of any one way is not deemed. to be necessary and would merely lead to confusion if incorporated in the drawing.

To effect the intermittent rotation of the ratchet wheel, I provide two pawls Z Z (one being one half a tooth shorter than the other) which are pivoted at the free end of a lever that is fixed at its other end to one end of a rock shaft which is supported in suitable hearings. On the other end of the rock-shaft is lined a two armed lever having arms Z and 0, one arm Z of which has a pin Z that is engaged in a slot in the lower end of a vertical rod Z the upper end of which rod is slideable in a groove in the vertical post 13 (see more particularly Fig. 1

Carried by the part (1 on the post B, is a bearing for a pin Z having an eccentric F that enters a long slot Z in the rod Z The pin Z will rise ant fall with the part '1" as the connecting-rod s imparts movement, as already described and the slot Z in the rod Z is long enough to permit of this.

The weight of the rod Z and of the levers Z, Z, on the rock-shaft Z will cause the said roclcshaft to turn in the direction to bring the pawls down relatively to the ratchet wheel L, the pawls, or one of them engaging in a fresh tooth in the wheel. (Springs 1: act to bring the pawls into engagement with the teeth.) When next the part C is raised, the pin P will contact with the upper end of the slot Z in the rod Z and will lift the latter this in turn rocking the shaft Z and causing its lever Z to lift the pawls and rotate the ratchet wheel and thus impart movement to the knife carrier and knife.

In order to limit the extent of the aforesaid movements, 1 provide means to adjustably limit the upward movement of the arm 0 of the said two armed lever, and thus, to a corresponding extent, limit the downward movement of the rod Z and pawls The means I provide for the purpose aforesaid, consists in a vertical cylinder 0 adapted to be rotated in a suitable bearin The lower end of this cylinder is formed with a number of steps 0 all at progressive different altitudes, and these steps are adapted to form stops against which a pin 0 on the lever 0 will contact. Accordingly there fore, as the cylinder 0 is set so will the extent of the upward movement of the lever r) and consequently, through the mechanism already described, of the downward movement of the pawls Z Z be determined.

As shown in Fig. 2, the cylinder is set to permit of the very minimum of movement of the lever 0. This may be such that the two pawls Z lt'will set. alternately toad-Q vance the ratchet wheel through thepdistance of one half of one of its teeth, and at this rate the micrometer screw will advance the knife so that sections of .001 mm. thick;

The part Z of the'pin Z (see Fig. 1) is made eccentric so as to enable exact adjustment to be effected.

In order to'prevent accidental over-run: ning of the slide T, if the operator, after sectioning several successive blocks of ma.-

terial. should fail to again set back the slide 7 T and the knife, I provide a, brake device. n A. 1

LlllS may COllSlSb of a rod 1 on the slide and a rod to on say the frame of the machine;-

or carried by the part C. Or any other, suitable braking device'may be employed.

The ratchet wheel will be enclosed by a casing or cover 20 and I may provide a springQ. to take up back-lash.

I claim:

1. In amicrotome, the combinationwith a base, of a post risingtherefrom, a carriage held against and slidable; vertically on the post, a subject-holder mounted on the carriage, a slide mounted on the base, a knife supported by said slide, a feed screw for feeding the slide, an operating shaft, connections between said shaft and said carriage, and means to actuate the feed screw from said shaft.

2. In a microtome, the combination with a base, of a post rising therefrom, a carriage slidable vertically on the post, a subjectholder sustained by said carriage, a slide on the base, a knife supported by said slide, a feed screw for actuating the slide, an operating shaft, connections between said shaft and slide, and micrometer pawl and ratchet mechanism for actuating the feed screw from said shaft.

3. In a microtome of the type described in claim 2, the combination with said feed screw having a ratchet wheel thereon, a rocking lever carrying pawls to actuate the ratchet wheel, means to actuate the lever from the shaft, a pin on said lever, and a rotatable cylinder provided with stop shoulders at its end to engage said pin thereby to limit the oscillating movement of the lever.

4:. In a microtome, the combination with a base, of acolumn rising therefrom, a subject-holder supported to slide Vertically on said column, a slide mounted on the base, a knife-holder carried by said slide, and a a base having Ways, of a slide slidable in said 1. fit) ways, a knifesupport carried by said slide,

a rotatable knife-holder sustained by said support, a spring device tending to rotate the holder in one direction, a screw device by which it may be turned in the opposite direction, and means to lock the holder on its support.

7. In a microtome, the combination with a base, of a column rising therefrom, a sub ject-holder slidable on said column, a knife support slidable in said base relative to the column and holder, and a micrometer screw feed device acting directly on said knife support.

8. In a microtome, the combination with a base having ways, of a slide operating in said ways, a column rising from the base, a bearing slidably mounted on the column, a subject-holder carried by the bearing, spring-actuated means to maintain the bearing firmly in contact with the column, and a. knife-holder carried by the slide.

9. In a microtome, the combination with a base having ways, of a slide mounted in said ways, a knife support carried by said slide, and a wedge device to cramp the support to the slide.

10. A microtome of the type referred to having in combination a base, a slide bearing in said base, a micrometer feed screw connected to said bearing and located within the base, a driving spindle, rocking levers carried by said spindle and means operated by said levers to impart intermittent rotation to said screw.

11 In a microtome of the type referred to, the combination with a base, a column rising from said base and a carriage slidable thereon, of a subject-holder carried by said carriage and devices for adjusting and look ing the holder relative tothe carriage.

12. In a microtome of the type referred to, the combination with a base, a column rising therefrom, and a carriage slidable thereon, of a subject-holder carried by said carriage and devices for adjusting the holder around axes at right angles to each other.

13. A knife-holder for microtomes em- I bodying a knife support that is rotatable in said holder, a cramping device to fix the knife in said support, a spring acting to rotate the support in one direction, a screw to rotate the support in the opposite direction, and a cramping device to clamp the support in the holder. 7 MARK THOMAS DENNE Witnesses CHAs. BAUER,

J. C. MATTHEWS.

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