HARD-ALLOY

TOOL

PHOTOGRAPHIC T.

FOR

CUTTING

MOTION-PICTURE

FILMS A.

UDC

Livshits

621.9.025:771.531.3

The All-Union Scientific-Research and Design Institute of High-Melting Metals and Hard Alloys (VNNIITS) carried out experimental work on increasing the strength of a tool used for cutting motion-picture photographic films. To make the tool, the institute used cermet hard alloys with high hardness (HRA 88.5), significantly exceeding the hardness of tool steels, and high wear resistance. Wear-resistant knives for cutting motion-picture photographic film were made of VKIOM nonstandard hard alloy (90% WC, 10% Co). The fine-grained structure (the grain size in the basic mass is not greater than 1 ~) of this alloy makes it possible to obtain a sharp cutting edge and to machine articles with abrasive and diamond tools. It is technologically difficult to make hard-alloy knives for the upper shaft of cutting machines having the shape of a plate over i00 mm in diameter and 2 mm in thickness. Therefore, the hard alloy was used to make only the knives of the lower shaft. Plant tests showed that, during operation with hard-alloy knives, the tool-steel knives of the upper shaft sharpen themselves, as a result of which their strength is increased. The knife of the lower shaft (Fig. i) consists of a steel body and a hard-alloy cutting ring. The rings were made from plasticized blanks. The pressed and presintered blanks, of simple geometrical shape (bushes), were soaked with paraffin and machined on metal-cutting equipment. The sequence of calculating the tolerances for final machining and the allowances for manufacture and the dimensions of the plasticized blanks for various articles is known.* During machining of the plasticized blanks, it is necessary to take into account their low strength (flu ~ 2 kg/mm2), low hardness, and high brittleness. It is necessary to use hard-alloy tools to machine plasticized blanks containing hard particles of high-melting-metal carbides because steel tools undergo rapid wear under these conditions. The metalcutting tool must be well sharpened and honed because the use of a dull tool causes chipping of the alloy and reduction of the cleanness of the machined surface. After machining, the rings were subjected to final sintering. Then they were polished along the inside diameter and on the face side adjacent to the steel .

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~

body.

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It is technologicallydifficult to join the rings and bodies by weldingbecause the ring can break because of the large differencein the coefficients of linear expansion of the steel and hard alloy. Sincethe load on the tool during cutting of the filmis insignificant,the parts were joinedwith an epoxy-resinbased adhesive. The ring, glued to the body,was machinedalongthe outside

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I

~I

~

d i a m e t e r , a f t e r which the c u t t i n g edge was s h a r p e n e d .

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carried out on grinders with diamondtools.

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Fig. i. Knife of the lower shaft of the cutting machine: i) body; 2) hard-alloy ring. Translated

These operations were

Plant tests at one plant showed that the strength of the hard-alloy knives is significantly greater than the strength of the steel knives which used to be used (the shaft with the steel knives used to be resharpened three times a month, and the shaft with the hard-alloy knives operated without resharpening for over two years). *V. A. Ivensen, Manufacture of Multiblade All-Hard-Alloy Tools and Articles of Complex Shape from Plasticized Blanks [in Russian], Tsvetmetinformatsiya, VNIITS, Moscow (1963). from Khimicheskoe

i Neftyanoe

Mashinostroenie,

No. 2, p. 26, February,' 1971.

9 197I Consultants Bureau, a division of Plenum Publishing Corporation, 227 West 17th Street, New York, N. Y. 10011. All rights reserved. This article cannot be reproduced for any purpose whatsoever without permission of the publisher. A copy of this article is available from the publisher for $15.00

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