US1700663A - Method of grinding threads - Google Patents

Description

' J. BATH METHOD OF GRINDING ,THREADS 2 Sheets-s 1 Original Filed Dec. 27, 1921 L ho.

Jan. 29, 1929.

J. BATH METHOD OF GRINDING THREADS 8 vweufoz Hozn 3 2 Sheets-Sheet 2 llllllLlnlull-l'lulllll'l Original Filed Dec. 27, 1921 w mw vlo

Patented Jan. 29, 1929.

entree era-res toxin BATH, or wonon's rsn,MAssAeHusETrs.

METHOD or eRI-NninG rnREAns.

" Original application filed December 27, 1921, Serial No.'52 4,817. innate and th isappl icatio n filed July Y 13,1925. Serial No. 43,418. a

This invention relates to amethod of grinding threads and isa division of my prior ap- Tplication, Serial No; 5524;817', filed December 27,1921 and-patentedFebruary 28, 1928, No. 1,660,468. Y

It is thegeneral object of mypresent invention to i provide a method of grinding threads on taps, thread-gauges, screws, and similar articles by which the operation of themachine may be made substantially continuous, with the grinding wheel acting on the work in both directionsof axial travel.

In the attainment of thisv object I provide a novel sequenceof operationsby which'the back lash of the machine is taken up at the completion of each cut by the grinding Wheel in each direction and by which the wheel is accurately alignedwith the preceding cut tuponits return travel. V

Y My invention further. relates to certain details of operation which will be hereinafter described andmoreparticularly pointed out "intheappendedclaims. Y

A form of mechanism suitable for the carrying out of my improved method is shown in the drawings, 1n which y Fig. 1 1s an end elevatlon of a drlving spindle and work driving attachments thereon adapted for proved method; I I i Y Fig. 2 is asectional elevation taken along the line 22 in Fig. l;

Fig. 3 is aipartial plan view looking in'the direction of the arrow 3 in Fig. 2;

Y taken respectively along the lines4-4 5-5,

6-6, 77 of Fig. 1; I

-Fig.'8 is a plan view of certain parts ofthe' machine, illustrating the procedure by which the amount of backlash is determined Fig. 9 is a detail sectional elevation taken along the line 99 in Fig. 8; and

Y Fig. 10 is an'end elevation looking in the direction of the arrow 10 in Fig. 8;

Referring particularly to Figs. 1 and 81 have shown'parts of a thread grinding machine including a head'center'mounted in a spindle rotatable in bearings in a head mounted in a tail stock 93. A grinding wheel W is mounted on awheel shaft 37 rotatably supported 'on a'wheel table 34 slidable on a .IIiOUIltQd. A ma es is slidablyadjustable in plication above identified.

'ters of the machine. the carrying out of my 1111- 111 'isfshown as extending through this slot,

Figs. 4 5, 6 and? are detail sectionalviews I while the screw 112 extends through a hole in guideways 49 and '50 in the wheel table" and may be clamped thereto by bolts 51. .A lead screw 46 is rotatable in'afiXed'beari-ng. 47

and engages the nut 48 to reciprocateth'e vwheelta ble. The screw '46 is connected to rotate wlththe spindle 60 by a train ofgears .56, 57 and 58 so thateach rotation ofthe spindle and work corresponds to a definite axial movement of the wheel. 5 For .a more complete description of the parts above referred to, reference is made to the prior ap Inthe operation of my improved grinding Y 'inacliine, I use work, driving devicesof novel construction which devices will now be de- 'scr1'bed particular reference being made to 0 Figs. 2 to 7.

The usual face plate is threaded onthe end of the spindle 60 and isprovided with a hub or extension 106'on which is mounted a' ring 107 supporting apair'of work driving 'dogs 108. These dogs'are radiallyj adjustable on the ring'107 and/are; secured thereto by binding screws 109.; The inner ends of the dogs are shaped to 'receive and engage" the whichis mouhted'onthe head and tail cen- The ring107 is flanged and isheld against,

the face plate by an outerring110"securedi to the faceplate bybinding screws 111 and v 112 (Figs. 1 and 7) A slot 113 extends nearly around the ring 110 and the binding screw tionsll'? (Fig. 6): fitting the segmental slot 113. These blocks are "secured in 'iangular adjusted positionby clamping bolts "118 and nuts 119 (Fig. 5). A spring handle'120 is secured to each-"block or 116 a 'nd is.provided with a spur 121' engagingnotches 110 Y I formed at the outeredge of theringillO. f stock 32 and also including a tail center 90 l A similar spring handle 1'22is se'curedtothe inner ring 107 ,this handle being provided with a socket or recesszl23 adapted toreceive pins" or "studs 124 formed dnxtheends of the bolts 118 which secure the blocks 1.15' and-116 in position. Sto{ps;125 and-126:;(Figsn1-and 4) are also slidable inthe slot 113 of thering so I shank of a tap or other article to be ground 110 andmaybe clamped in position as will theback lash in the connections between the work spindle and the grinding wheel table. The extent of this angular adjustment .of thework required with a particular set-up of the machine is determined experimentally by useof the indicating device shown in Figs. 8to10. I

' An arm130 (Fig. 8) is fixed on the lead screw nut 4:8 and-extends forwardly and upwardly to a position for engagement by the .shortend of an index lever 131, pivoted at .132 on a stand 133. The stand is adjustably secured'to thehead stock 32 bya clamping bolt 1341. A lockplate 135 is slidably mounted in guideways 1 36 on the head stock 32 i and may be secured in adjusted position by a clamping bolt 137. An index or zero line is formed on one of the guide-ways136 as a reference mark for-the index lever 131.

coincides .with way136.-. i

In order to determine the exact amount of back lashin the connections between the spindle and the-wheel table, the spindle is moved .in the direction in which it has been rotating ,until the handle 1220f the dog supporting ring 107 is aligned with the jaws of the lock plate 135.. This plate is then advanced in itsguideways 136 until it releases the handle 'from the pin or stud 124 on which it has been seated and looks it from further angular, movement. The stand 133 ofthe index lever or pointer 131 is then adjusted so that the rearend 01": the pointer will be pressed against the arm 130 by thepointer spring 138, while at the same'time the other end of the pointer the zero mark on the guidevThe spindle is then turned backward or in the oppositedirection to that in which I it has been rotating until the lead screw 46 begins to move. the nut 48, such movement being instantly indicated by movement of the pointer 131. The second sliding block 115 or 116 is then moved to bring its stud124 into alignment with the recess in the handle 122, in which position it is then secured.

1 ith'the positionsof the blocks 115 and i 116 thus. accurately located, it is -merely necessary to'swing the handle 1 22 from one :stud 124C to the other, when the direction of the table teedis reversed to cause the grinding wheel to accurately follow the thread in 1 both directions of table feed. If it is found that .the :wheel when thus adjusted engages slightly harder on one side than 'on the other,

- one'of- theblocks 115 or 116 may be further adjusted by. moving its handle 120 one: or

more notches along the ring 110. -VVhen adjustment is once-made for a parthe connections between the ticular set-up of the machine, no further attention is necessary beyond. swinging the handle .122 from one stud 124 to the other at each end of the wheel travel. The output of the machine is thus greatly increased, as the usual idle return feed of the grlndlng wheel is entirely avoided.

When grinding certainetypes of thread, such asthe Acme thread, itis sometimes desirable to feed the wheel sideways to widen the thread groove. The stops 125 and .126 are-th on used to preserve the original setting so that the slides115'0r 116 maybemovedf the required number ot notchessideways to widen the thread and may then bewreturned to their original positions when a new thread is to be ground and widened. J

The face plate 105 may be providedwith graduations as shown in Fig. 3and the ring 110 may have an index mark cooperating therewith to indicate the angularirelation of these parts. These graduations areuseful when it is desired to advance the ring a certain angular amount relative to the face plate. r Y.

I Having thus described my improved met/h od it will be seen that this method renders the grinding operation substantially contins uous and entirely eliminates theyidlereturn run of the wheel which hasbeen' the usual prior practice. I am also-able to'take up the back lash by a very simple manual operation after a machine has once been set for the work to be ground andthe output'ot the machine is very greatly increased over the amount of work which can be done when grinding in one directiononly. 1

This method of grinding has been particularly described with reference -to-' grinding taps but it is to be understood that the method .is equally applicable to grinding screws,

worms, thread gauges and any other articles of a similar nature in which threadsor helical grooves are to be produced by grinding. Having thus described my invention and the advantages thereofI do not wish to be limited to the details herein disclosed other: wise than as set forth in-the claimsbut what I claim is 1. The method of grinding threads which comprisestaking a grinding cut with the work rotating in one direction, makinga'relative adjustment of parts between the work and the wheel equivalent to the back lash in Work and wheel, and then taking a second cut over the same threads with the direction of rotation of the work reversed and with thewheel moving axially along the work ina direction reversed to that of the firstdescribed cut, the

direction of wheel 'ieed reversed.

comprises taking-a grinding, cut with the work rotating in one direction, angularly adjusting the work a-definite predetermined.

' amount, and taking a second cut with the work rotating in the opposite direction.

3. The method. of grinding threads which comprises taking a grinding out With the work rotating in one direction, adjusting the vwork an amount equivalent to the back lash between the Work and the wheel, and taking work rotating in one direction, angularly ad, I .justing the work relatively to-the spindle an amount equal to the back lash between the work and the wheel, and thereafter taking 15 a second cut with the work rotating in the opposite direction, the wheel remaining in position advanced toward thework during all steps of the operation.

In testimony whereof I fixed my signature.

JOHN BATH.

have hereunto af-

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