<> In this machine, a multipoint cutter is rotating against the workpiece and material removed from the workpiece accordingly.. This is done by connecting the worm shaft to the milling table feed screw with the help of a set of gears. <> The crank has an arrangement in connection with the plunger-pin, which can slide through the slot and the crank is pivoted at the centre of a disc. endobj Before uploading and sharing your knowledge on this site, please read the following pages: 1. Since the crank and spindle ratio is 40 : 1 and hence when the crank moves through one revolution, the spindle or the job moves through 1/40 of revolution, i.e., the job will revolve through an angular movement of 9°. For quick-placing of plunger and in order to avoid the counting of holes, fixed arms (sectors) are provided which can be set apart at any number of holes desired. Terms of Service 7. 6 0 obj �����K�]G�#d���x��. 16.61. <> Prohibited Content 3. Generation of flutes on twist drills, milling of helical and spiral gears, milling of worms and cutter, etc. The formula given below holds good for the change gears. Most heads are based on a Bridgeport design and have been cloned by Taiwanese and Chinese manufacturers. Types of Drill Bushes | Jigs | Machine Tools | Industrial Engineering, Unconventional Machining Processes: AJM, EBM, LBM & PAM | Manufacturing, Material Properties: Alloying, Heat Treatment, Mechanical Working and Recrystallization, Design of Gating System | Casting | Manufacturing Science, Forming Process: Forming Operations of Materials | Manufacturing Science, Generative Manufacturing Process and its Types | Manufacturing Science. endobj �@E����[��ffv�$EAq�B,D4������`5͝s�E4C�M�q�sU��V2D�"�"B���V��ZE�E����~��&���w��k����L�4>��+&|��h`�d6#c3���шFZ�Zh��'Z ��|Ft��� The following types of index-plates having the holes given against them are available. In such cases, differential indexing is found to be more suitable. <> So for each tooth, the worm will be rotated by 12 holes of 18 hole circle with the help of the crank and then the index plate is rotated by 22 holes of the 27 hole circle. It helps to divide the job periphery into a number of equal divisions, i.e., square, hexagonal octagonal, etc. Lead of helical milling machine is the distance through which the table moves when the spindle of dividing head moves through one revolution without any change in velocity ratio between the dividing head spindle and the table feed screw. One of the important indexing operations to be performed on milling machine is the helical or spiral milling. 4 0 obj Meaning of Indexing 2. endobj The operation of rotating the job through a required angle between two successive cuts is termed as indexing. endstream endobj [gravityform id="1" title="false" description="false" ajax="true"]. 8 0 obj Let us take an example of a gear blank on which 64 teeth are to be cut. • Milling machines are very versatile. The rotating tool consists of multiple As the handle is turned, the index plate also turns, but at a different rate and perhaps in the opposite direction. <>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 595.44 841.68] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>> Differential indexing makes it possible to rotate the work by any fraction of revolution with the usual index plates furnished with the equipment. c. The job is to be fed to the cutter by the table move­ment. x�u�Ok1�{ ����L�[ă�-]�Az(V���v���H-����7����Y�ԛ%h>�bY�K Available number of index plates with different hole circles, sometimes confine the range of plain indexing. •Used to divide circumference of workpiece into equally spaced divisions when milling gear teeth, squares, hexagons, and octagons. Milling machine another most important machine tool after the Lathe machine tool and drilling machine.. Vertical Milling Machine is Most Common. There must be a proper relation between the move­ment of job and table. Methods of Indexing 3. Content Guidelines 2. are some of the examples of this class. endobj Plate 1 : 24, 25, 28, 30, 34, 37, 38, 39, 41, 42 and 43. stream INDEX CORPORA,TION MP - 1M - 10/ 75 Repr. x��[[oܶ~7�����¦EI���.�$=qЇ��b;u���*���!g(��4��(���r�}3��{�j����ً�����.��_����]~�as{_l��e��%{�� {}}zr�`)O#v���D0O�'X(y�8�x�믧'��?~==�k������NO~V�z�Zɏ��Eˆq��h�l�p�в��7�X���x,�R |;=���"�+����g��h��ӓ?b����H!�:H֪ �Cc��l�������;*��!C=T�Y洐C��N�?�ԣ܌x���J����2���pO�iC���O�#y,�m��L���P�h��4T21�"%� a��Ȱ��Ad�gi�yE"�ɓ�CW�s!W���`�p��tu��g��QPT�����7�o�w����e��8��q����Pˆ�P���n�.��~��=�W�t���Q� �������_�[�կ���U?����->���TA #���'а�0੯?��1#�|.i��D��gH`m1��Odh���R>���X�sb�ʐH����ˣ�I>m�P*��?žb�NF�q�}�#� �D�4���`��$�kQס��"W{�e��^��0�*��d��#z�c���fz� Its primary purpose was that of indexing and rotating work in Spiral Head conjunction with the movement of the table for cutting flutes in twist drills. Helical of Spiral Milling. Introduction to Machining: Milling Machine. endobj <>/Font<>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 720 540] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>> To rotate a job through required angle, one needs: (ii) A source which can ensure that the job has been rotated through the desired angle. Wells-Index mills have a completely different milling head design than any other milling machine in the world. endobj The rotation of crank is transmitted through a gear to the job, so that the number of complete revolutions will result in certain revolutions of the job. 1 0 obj If it is desired to index a job by 35 degree, then the index head movement required to perform the operation will be = (35/9) = 3(8/9) = 3 + ((8 X 3) / (9 X 3)) = 3 + (24/27), i.e., the crank must be turned three complete revolutions plus 24 holes in the 27-holes circle. %PDF-1.5 This type indexing is most commonly used for indexing fixture. Account Disable 12. 1.9 Milling Machine Operations 1.10 Indexing 1.11 Index Methods 1.12 Indexing Procedures 1.13 Summary 1.14 Answers to SAQs 1.1 INTRODUCTION Milling machine is one of the important machining operations. The intermediate use of worm and worm-wheel is avoided. endobj %���� In this case, the dividing head has an index plate, fitted directly on the spindle. 10 0 obj endstream Uploader Agreement. "bk�Di yF8��x��K���st�R0��0Q��]�)��������Ң ]��,3�=�����Y"���J��Q9Sk)�j�u����B��?zj�np�Ǡ�T��m���;���W�R�����W����V�F�ra�,S×h�G�3�;�i�����Ei������=�N Q� This is done so that when the job advances and at the same time revolves also, the impression left by the cutter in the job will be identical to the contour of the cutter. In dividing head, the first requirement is met by an index-crank and the second by the index plate. Instead of rotating the job through certain division on its periphery, sometimes it may be needed to rotate the job through certain angle. The index plate has 24 holes and the periphery of job can be divided into 2, 3, 4, 6, 8 and 12 equal parts directly. Generation of flutes on twist drills, milling of helical and spiral gears, milling of worms and cutter, etc. The di­rection in which the table is swiveled determines the hand of spiral. This crank can be rotated about the axis and the plunger can be fixed at any desired hole. 3 0 obj Milling operations sometimes, require the rotation of job correct to fractions of minutes, for each groove, slot etc., to be cut evenly on the job surface. Report a Violation 11. Disclaimer 8. The principle of operation of compound indexing is the same as that of simple indexing, but the only difference is that compound indexing uses two different circles of one plate and hence also sometimes referred to as hit and trial method. x���w|U��q��Pq� ����b�U]T�� ""`�P���H[�JD)��@BIEi���܄���q{�7gf��ܛ��z��C�=m�ν�;s�L^ @ѵ{��9�,X����O]/]�Ԩ�����Tt�\j����*���|JJ�:��gϚ�زc��cuѢE����ŋ�����ȿ~��lٲE�g~�ᇂ�zժU���m�V0] �>�@7�x. Angular indexing is used for this purpose. The difference of N and n causes the index plate to rotate itself in a proper direction relative to crank. In this article we will discuss about:- 1. endobj endobj stream <> <> endobj The principle of compound indexing is to obtain the required division in two stages: (i) By rotating the crank or handle in usual way keep­ing the index plate fixed. %PDF-1.5 stream During the differential indexing, the index-plate is unlocked and connected to a train of gears which receive their motion from the worm gear spindle. The index is fixed in position by a pin called lockpin. <>>> %���� The accuracy of spacing of teeth is very important particularly when the work is of precision character e.g., gear teeth, shafts, cutter teeth etc. b. Plate 2 : 46, 47, 49, 51, 53, 54, 57, 58, 59, 62 and 66. Dividing heads are provided with such standard set of gears. are some of the examples of this class. The table of the milling machine must be set at an angle (equal to the helix angle) to the normal position of the table. (ii) By releasing the back pin and then rotating the index plate with the handle. Content Filtration 6. <> Between the indexing plate and spindle of dividing head, a certain set of the gears is incorporated extra. <>>> 1 0 obj The following relation is used for simple indexing: T = 40/N, where T gives the number of turns or parts of a turn through which the index crank must be rotated to obtain the required number of divisions (N) on the job periphery. The ratio of crank and the shaft on which job is mounted is 40 : 1, i.e., when the index plate makes 40 revolutions, the job makes one revolution.

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