DE2429096C3 - Device for damping vibrations in the sample holder of a microtome - Google Patents

Description

neutrally in the axial direction by the resilient elements 12 is given. The resilient elements suitably consist of O-rings. Preferably these are as soft as possible, creating a low natural resonance frequency of the system arises.

By using U-magnetized toroidal cores, soft one on the sample holder arm surrounded by a fixed axis, it is possible to make the magnets large relative to the system as such shape, whereby relatively strong magnetic fields can be generated. There is also the advantage that a relatively large mass is used, which in conjunction with the soft resilient elements reduces the natural resonance frequency of the system.

Using the two U-magnetized toroidal cores also eliminates the need an external soft iron connection of the magnetic circuit. Such an external soft iron connection would reduce the magnetic field strength unnecessarily.

If damping is only required in the radial direction, then of course only the Copper flange 2 is required, while the copper flanges 3 and 4 can be omitted.

The F i g. 2 a shows the vibrations of a specimen holding arm without a damping device after this was initiated.

2b shows the movement of a test arm provided with the damping device.

The time scale is 0.25 sec / cm and the F i g. 2 shows the significantly improved damping achieved with the Device is achieved.

For this purpose 2 sheets of drawings

Claims (2)

1 2 The invention will now be explained in more detail with reference to the drawings, the 1. Device for damping vibrations- F i g. 1 shows the section through a preferred embodiment in the sample holding arm of a microtome, embodiment form, and the, ".., _
characterized by one of non-5 F i g. 2 shows the damping curves that are obtained from existing magnetic material and with which, if a damping device is used, the sample holding arm is firmly connected to the axis (1) which is or is not used .. with a low resistance material in FIG. 1, numeral 1 represents an axis, the end of which is provided with an existing flange (2), and two U- or both ends are fixed in a known manner or U-shaped magnetized toroidal cores "on the specimen holding arm of the microtome which is shown in (5, 6 ). which surround the axis (1) and is not shown with reference to the figure 2. 3 and 4 denote Hch are resiliently attached to the axis (1), with flanges made of a material of low resistance, the U-magnetized toroidal cores (5, 6) so suitably copper, which are fastened to the axis 1 berrelatively to each other, that is fastened between. 5 and 6 denote two U- or U-shaped them a constant air gap (8), in which 15 magnetized toroidal cores, which around the axis give the toroidal cores (5, 6) a magnetic field and whose poles preferably hold each other upright and the U-magnetized toroidal superposed, with the north pole of a magnet opposite core * · (5, 6) are attached so that the one above the south pole of the other magnet, whereby a flange (2) is surrounded by the air gap (8). optimal magnetic field generated in the air gap 2. Device according to claim 1, characterized in that. Through the brackets 7, the magnets indicates that the axis (1) is firmly connected to one another with three flanges, so that one constant see (2, 3, 4) made of low resistance material air gap 8 between the magnets. 9 and 10 is provided, where the U-magnetized toroid- denote two flanges made of soft iron. 11 refers len cores (5, 6) are arranged so that the resilient suspension medium on a resilient element Flange (2) from the air gap (8) 'enclosing the two U-magnetized toroidal cores in sen and that the outer flanges (3, 4) a mainly radial direction. 12 designated outside of the U-magnetized toroidal cores a resilient element for the resilient suspension of the (5, 6) within the leakage flux of the respective U-magnetized toroidal cores in a main U-magnetized one toroidal cores (5 or 6) with regard to axial direction. Find. 30 The mode of operation of the in F i g. 1 shown direction is as follows: the armpit is fixed to the Sample holding arm connected. The on the rehearsal The present invention therefore relates to a supporting arm-acting vibrations Device for damping vibrations in the transmitted to the armpit. The U-magnetized Sample holder arm of a microtome. 35 toroidal cores are resilient with respect to the axis In the case of a microtome, e.g. B. an ultramicrotome, and its movement relative to the axis is a sample to be cut into thin slices is therefore subject to a delay. Attached to a Beweam specimen holder. In general, when moving in the radial direction, the copper writes the specimen holding arm an up and down flange 2 perpendicular to the magnetic field, which by moving during the advance against a fixed 4 ° the two magnetic cores in the air gap 8 between the standing cutting edge, the makes a cut with each downward movement of the pole of a U-magnetized core and the pole of the specimen holding arm. The other core is generated. Corresponding to the known suspension of the specimen holding arm, eddy currents must arise in a way that enables the implementation of these different copper plates. The specimen holding arm is picked up in a susceptible manner. In this way, the vibration is exposed to vibrations that are damped during cutting or movement,
external mechanical disturbances arise. So that the flanges 9 and 10 Cut pieces of the best possible quality obtained have the purpose of reducing the leakage flux of the U-magnetized it is appropriate to conduct these vibrations so far as toroidal nuclei so that the flux losses to be eliminated as much as possible by reducing the sample. In this way, there is a holding arm with a type of damping device, a sufficiently large magnetic flux in the air gap 13 and will see. The purpose of the present invention 14 so that with axial vibrations relative to the is to provide such a damping device. U-magnetized toroidal cores damping we- In the case of the damping device according to FIG. 55, incoming flows in the copper flanges 3 and 4 are present Invention will stand the effect of eddies. With an axial movement, e.g. B. in the figure flow used in a plate of a material to the left, the air gap 13 is reduced, thereby of low resistance arise when the plate eddy currents are generated in the copper plate 3, is crossed by a magnetic field. The air gap 14 is enlarged, causing vortices, The invention consists in the fact that flanges 60 are created in the copper flange 4 flows. The energy of a low resistance material, e.g. B. these eddy currents are decoppered from the axial movement, on an axis made of non-magnetic material, which is damped in this way. There rial, which is firmly connected to the sample holding arm and the air gap 8 is constant, no vortex is created, be attached. In the case of an axial flow, the copper flange 2 flows around this axis two U-magnetized toroidal cores, the 65 gung. The U-magnetized toroidal cores are in be held resiliently in relation to the axis. with respect to the axis 1 resiliently suspended, the The features of the invention are mainly due to the resilience in the radial direction 1 can be seen. the resilient elements 11 and the suspension main