US2192783A - Machine for forming helical gears - Google Patents

Description

March 5, 1940. E. L. ACKERMAN 2,192,783

MACHINE FOR FORMING HELICAL GEARS I Original Filed March 3l, 1937 2 Sheets-Sheet 1 March 5, 1940. E. 1 ACKERMAN 2,192,783

MACHINE FOR FORMING HELICAL GEARS Original Filed Marchl, 1937 2 Sheets-Sheet 2 5 'Ff 40 1 f i' 4] J fry/4, ,be/220x', daad/'d cf//Wa/z y f4/Wi, gli@ Patented Mar. 5, 1940 UNITED STATES orifice MACHINE FR FORMING HELICAL`GERS `Original application March 31, 1937, Serial No. 134,117, now Patent No. 2,174,814, dated October Divided and this application January 14, 1939, Serial No. 251,051

3 Claims.

This invention relates to a machine for making helical gears and is a division of my application., Serial No. 134,117, filed March 3l, 1937, now Patent No. 2,174,814: issued October` 3.939. The object of the invention is to provide a machine which involves the twisting of .pinion rod stock in long lengths to thereby twist the teeth of the pinion rod to form uniform spiral teeth longitudinally thereof during which operation the rod is held at its ends in a manner to submit the rod to a longitudinal strain during the twisting thereof.

Pinion rod stock which is provided with the teeth extending longitudinally thereof and is about eleven feet in length is not uniform in hardness, that is, it has hard and soft spots which will tend to prevent the metal twisting as readily at the hard spot as it will in a preceding or succeeding soft portion but, by placing the rod under 2G longitudinal strain suicient to prevent material shortening of the rod duc to the twisting,` the twisting strain is distributed practically uniformly from end to end of the rod thereby forming v the teeth in a true helix. 25 Heretofore, helical gears have been formed by gear cutting machines which is a somewhat expensive process and the purpose of this invention is to provide a method by which true helical gears may be formed at a minimum of expense and avoiding the cutting and handling costs.

These and other objects and various novel features of the invention are hereinafter more fully described and claimed, and the preferred method and means for performing the same is shown in the accompanying drawings in which- Fig. l is a side elevation of a machine constructed and adapted for use in the twisting of the rod, a gauge being provided that is n'lovable along the twisted rod to determine the extent to which the rod requires to be twisted to form the teeth on a predetermined helical angle.

Fig. la is an elevation of the machine taken from the right hand side of Fig. l.

Fig. 2 is a section taken on line 2-2 of Fig. l.

Fig. 3 is a section taken on line -sof Fig. l.

Fig. t is a section taken on line 4-4 of Fig. l.

Fig. 5 is an enlarged plan view of the gauge.

Fig. 6 is a side elevation of ordinary commercial pinion rod stock.

Fig. '7 is an end View thereof.

Fig. 8 is a side view of the rod after having been twisted.

Fig. 9 is an end view thereof.

Fig. 10 is a section through a formed helical gear taken on line lll-I0 of Fig. 1l.

(ci. s-7s) Fig. 1l is an end elevation thereof. Fig. l2 is a sectional View ci another form of helical gear taken on line I2I2 of Fig. 13.

Fig. 13 is an end elevation of the formed gear.

In Fig. l is shown a convenient form of machine for the twisting of a pinion'rod. This machine consists of a frame member l which may be of the common form of steel beam having top and bottom flanges 2 and 3 and a central web l therebetween. The bottom flange provides a means for attaching to leg portions 5 as by means of the bolts E extending through the bottom ange 3 as shown in Fig. 1. On the top flange at one end is secured a head l also by means of bolts 8 extending through a flange of the head into the upper flange 2 of the beam. Rotatably supported in this head is a rod holder il flanged as at Il! at its forward end to engage over the inner face of the lhead 'land provided with a v collar H secured to the body of the holder as by means of a screw l2 to engage the outer face of the head and prevent longitudinal movement of the holder in the head. The outer endof the rod holder, in the structure shown, has a worm Wheel i3 secured thereto which meshes with a worm I4 on the shaft that is driven by a pulley l5. As shown in Fig. la, there is a second pulley l5a on the shaft H5 and both pulleys are loose on the shaft and between the same is a clutch having two cone faces ill and lil shiftable by a lever ft2 to clutch one or the other of the pulleys l5 or a to the shaft. The rod holder El is inten nally toothed as will be understood from Fig. 4 and dts the end of the pinion shown in the same manner as internal and external gears mesh, .E there being sufficient clearance provided to permit ready insertion of the end of the pinion shaft IS longitudinally thereinto.

The pinion shaft is a commonly known article of commerce and may be obtained in lengths of about eleven feet but in so far as this invention is concerned, the length of the pinion shaft is not material. At the end of the beam l opposite the head is a tail stock il which is formed to provide internal gear teeth corresponding to the internal gear of the rod holder S and receives an' end of the pinion rod which extends thereinto in the neighborhood of an inch as will be understood from Fig. l.. The tail stock is provided with bolts i8 which extend into clamp elements i9 spaced from the base of the part Il to provide ways for the upper flanges 2 of the beam. This permits the tail stack to be moved longitudinally of the upper flange to properly position the same for different lengths of rod. Also, slidably mounted on the upper face of the top flange 2, is a gauge 20 having a base 2| of considerable width to normally sustain the gauge in an upright position on the beam and has an inwardly extending lower flange 22 and an upper ange 23, the forward edge of which is formed with oppositely inclined faces 2d and 25 as will be understood from Fig. 5. The pinion shaft or rod I6 is supported at its ends and lies in the recess between the lower and upper flanges 22 and 23 and the inclined faces of the upper flange are formed at the helical angle to which the teeth are to be formed and provide a visible means of determining the uniformity of the twist at any points of the shaft by simply sliding the same along under the eye of the operator. One face 24 is used to gauge a right hand spiral and the other a left hand spiral either of which may be formed by reversing the direction of rotation of the rod.

go Bearing in mind that pinion rod stock has hard and soft spots, there may be a portion or several portions of greater hardness than intervening portions which may not twist as readily as the softer portions thus tending to distort the helical line passing from the soft spot through the hard spot or vice versa. The operator, as the rod is being twisted, may discover such slight distortions by using the gauge and, by means of a wrench of the proper form which is merely indicated by dotted lines 26 in Fig. l, the shaft may be turned at that spot by manually applying strain to assist the twisting or to retard it to maintain the twist of the shaft to form the teeth in a uniform helix from end to end.

The twisting of the shaft is produced by the gear train heretofore mentioned which is operated by power and may be provided with a means for stopping or starting the twisting movement as, for instance, by a shifting of the belt on the pulley l to an idle pulley or from the idle pulley to the pulley l5. With the power applied to the pulley l5, the shaft is held stationary in the tail stock and is rotated in the head stock the desired number of turns to form the teeth on the desired helical angle. The twisting is comparatively slow due to the speed reducing gear train and thus by the sliding of the gauge along the rod as the twisting progresses, the operator can at all times readily note the progress of the work or spots where the twist is retarded or accelerated as by too hard or too soft spots in the metal and can stop and start the machine as may be required while trueing a portion of the rod by means of the wrench device 26 as heretofore described.

It will be noted that the rod in the machine shown is not fastened in either the head or the tail stock. This is the preferable method and the rod extends into the head and tail stock a suflicient distance yto insure sufcient surfaces in pressure contact under the power applied in twisting to prevent material slippage, that is, to insure tension being applied to the rod during the twisting. Without some means being provided to place longitudinal tension on the rod, it will not, although twisted, be uniformly twisted and even with the ends of the rod being held from movement in the head and tail stock there still are portions of such hardness or softness as to require manual application to either assist or retard the twisting at such spot.

The rod, as shown in Fig. 6, is the usual pin-I ion rod and Figs. 8 and 9 show the twisted rod having the teeth of the pinion rod formed on a helical angle in the manner hereinbefore described. The twisted rod is introduced into an automatic machine of the type now in use with the rod stock of Figs. 6 and '7 and sections are formed and cut off from the end of the rod which feeds into the cutter as each part is formed. There are two gear forms shown in Figs. to 13 inclusive. In Figs. 10, and l1, the gear is formed with a recess 30 in one face and the teeth are cut back as at 3l which is required for certain use of such a gear or the gear may be formed as shown in Fig. 12 with a pilot 32 at one end and an extending shaft 33 at the other side, the teeth 3d being substantially the same as in Fig. 10.

I have not described the special machines (which are of the screw machine type) that may be utilized in the cutting of the gears as such machines are well known. In forming a gear having the pilot 32 and the shaft portion 33 of Fig. 12, the twisted stock is cut to below the roots of the teeth to provide the intermediate section having the teeth 34 each of which will be on the true helical angle and practically as perfect as have been produced by previous known methods. Other gear forms may likewise be readily made with side faces of the desired shape either with or without hubs. In the cutting of a gear in a gear cutting machine the stock used is approximately the total length of the final gear and requires handling in positioning the machine for cutting the teeth and in other machines for forming the pilot and shaft portions or in the case of the form shown in Fig. l, after the gears are cut, the gear is bored and counter-bored, in all of which previous operations there is time and labor loss due to the necessity of introducing the small parts into the machine and removing therefrom etc. In my improved method, I avoid the excessive costs in the cutting and in the formation of the nal gear due to the fact that the teeth are formed on a helix by a mere twisting of a rod of a length materially greater than the width of the gears to be cut therefrom to provide a large number of gears. The twister rod is then fed into an automatic machinev having cutters which work upon the rod end and each is formed for cutting from the twisted rod and the rod then moved forward to position the end thereof for a succeeding operation.

Thus, in the formation of small helical pinions, for instance, the labor cost is very materially reduced in that once a rod is placed in the automatic machine, it is continuously fed thereinto as the gears are formed and cut from the end thereof without necessity of manipulation by an operator, that is, if the rod is ten feet long and the gears were an inch long, the positioning of one rod in the machine would be the only hand operation required for in the neighborhood of one hundred and twenty gears. This, of course, would vary with the width between the side faces of the gear including the .pilot or shaft portion.

By the above described method, a helical gear of considerable length may be provided. Due to the twisted rod having the teeth formed on a true and uniform helix, the helical gear can be used in mesh with the original pinion rod having the spur type of teeth when the twisted rod has its axis lying at the helical angle to the axis of the spur gear. There will, of course, be some friction if the gears are held from longitudinal displacement but in many cases, especially where there is not a rapid rotation of the gears as in many machines, the friction is negligible. Therefore, my improved method is not confined to the formation o1' gears of short face widths or to the shapes of gears shown in Figs. 10 and 12.

In the machine shown, the pulley i521 is driven by a cross belt 43 which enables the shaft I4 to be turned in an opposite direction from that by which it is driven by the pulley l5. The rod holder 9, due to its worm and a worm gear drive, cannot unwind to release the pinion shaft from frictional engagement in the head and tail stocks and the above described arrangement permits reversely rotating the head stock to release theV tortional strain on the pinion shaft, and the arrangement may be used to make right or left hand helical gears.

From the foregoing description, it is believed evident that the various objects and features oi the invention are attained by the structure described; that the machine provides for rapid manufacture of helical gears at materially less cost than the usual cut gears of the helical type due to the comparative low cost of the pinion rod which is of standard manufacturing and is made in large quantity not being much more expensive than solid rod.

Having thus fully described my invention, its utility and mode of operation, what I claim and desire to secure by Letters Patent of the United States is:

1, A machine for twisting pinion ro-d stock to change the teeth from spur to helical form, comprising a. base, a head stock and a tail stock thereon, each of the head and tail stocks having internal teeth to iit the spur teeth ci the rod at the respective opposite ends, means for rotating the head stock totwist the rod, and a gauge movable on the base parallel to the axis of the rod and having a portion at an angle to the rod axis for determining the helical angle to which the teeth are to be formed.

2. A machine for twisting pinion rod stock to change the teeth from spur to helical form, comprising a base, a head stock and a tail stock, each provided with teeth to fit the spur teeth of the rod at the respective opposite ends, means for rotating the head stock to twist the rod, and gauge slidable longitudinally of the base and having a gauge face positioned at the same angle to the longitudinal axis of the rod as the helical angle of the teeth to be yformed by twisting the rod.

3. A machine for twisting pinion rod stock to change the teeth from spur to helical form, comprising a base, a head stock and a tail stock thereon, each of the head and tail stocks having internal teeth to fit the spur teeth of the rod at the respective opposite ends, means for rotating the head stock to twist the rod, said means comprisingy a Worm gear connected with the head stock, a worm for driving the worm gear, means for rotating the worm in a right or a left hand direction at will, and a gauge slidable on the base parallel to the axis of rotation of the rod and including oppositely disposed faces at an angle to the longitudinal axis of the rod respectively corresponding to the helical angles to which the teeth are to be formed by twisting the rod on its longitudinal axis in either a right or a left hand direction.

EDWARD L. ACKERMAN.

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