Cutting – With means to convey work relative to tool station – Plural passes of diminishing work piece through tool station
Patent
1981-09-17
1985-01-29
Yost, Frank T.
Cutting
With means to convey work relative to tool station
Plural passes of diminishing work piece through tool station
83414, 83714, 839155, G01N 106
Patent
active
044958447
DESCRIPTION:
BRIEF SUMMARY
This invention relates to rotary microtomes, by which is meant microtomes in which relative incremental advance movement between a specimen table and a relatively reciprocable knife, and the reciprocating movement itself are both derived from a single rotatable drive member. The typical increment of the advance movement is some 4 microns in the case of specimens embedded in paraffin wax, and some 0.5-1.0 microns in the case of samples embedded in synthetic resin.
Conventional rotary microtomes provide the advance movement by means of a leadscrew which acts on a linear dovetail slide carrying the specimen table. This provides a robust mechanism which is well able to withstand the cutting forces involved, but in practical use, the arrangement is likely to suffer from friction and sticking and attendant vibration, which interfere with the accuracy of the advance movement. This is particularly the case in rotary microtomes designed for specimens embedded in synthetic resin, since in these it is necessary to provide for specimen retraction between successive cutting strokes, in order to prevent the last-cut section from re-adhering to the sample under the effects of static electricity during the return stroke. This retraction is conventionally of some 50 microns or so, and re-setting of the specimen advance after such a retraction is rendered unreliable, particularly where, in addition to the friction and sticking effects associated with the dovetail slide referred to above, the leadscrew itself is moved bodily to permit the retraction.
The present invention is concerned to provide a specimen table advance mechanism for a rotary microtome in which the effects of friction and sticking and vibration are largely eliminated, in which the cutting forces involved are well catered for and which can be adapted for both paraffin-embedded and synthetic resin-embedded specimens without substantial re-design of the basic arrangement.
Basically the present invention provides a rotary microtome in which the advance movement of the specimen table relative to the cutting member is provided by a parallelogram linkage. As will be readily understood from the subsequent description of a specific embodiment of the invention, the parallelogram linkage may itself also act as the support for the specimen table. To eliminate friction and sticking entirely from the points of articulation of the parallelogram linkage, they may be constituted by strip hinges.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a schematic view in side elevation of the specimen table support and advance mechanism of a rotary microtome for synthetic resin-embedded specimens, with portions cut away for illustration;
FIG. 2 is a view corresponding to FIG. 1 but with additional portions removed and cut away to more clearly illustrate the hinges; and
FIG. 3 is an exploded perspective view of the microtome of FIGS. 1 and 2.
DETAILED DESCRIPTION
The mechanism in the drawings is supported on the massive base 1 of the microtome, which base is apertured at 1a and 1b for the passage of parts of the mechanism. A knife 2 is fixed to the base by conventional means (not shown in the Figure) and a specimen 3 is shown as mounted on a specimen support 4 which is carried for reciprocating movement vertically relative to the knife (as shown by the arrow 4a) on a dovetail guide 5 which together with the specimen support 4 constitutes the specimen table of the microtome. The guide 5 is rigidly fixed to a bracket 6 which forms an upper limb or lower horizontal link of a parallelogram linkage whose lower limb is constituted by a pedestal structure 7 secured fast to the base 1. The sides of the parallelogram are formed on the one hand by a vertical link 8 adjacent the dovetail guide 5 and on the other hand by an upper vertical portion of 9' of a member generally indicated at 9 through which both advance and retraction of the specimen table are effected. Articulation of the parallelogram linkage is provided by four paired sets of crossed strip hinges indicated at 10a-d, each set having a
REFERENCES:
patent: 3771405 (1973-11-01), Blum
patent: 3785234 (1974-01-01), Sitte
patent: 3955638 (1976-05-01), Wasko
"Handbok I Finmekanik", Bartil Ejerhed, (English translated version).
Jackson Brian L.
Parker Philip
Phan Hien H.
Yost Frank T.
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