US1998108A - Torque transmitting member and method for producing the same - Google Patents

Description

April 16,19 wA s 1,998,108

TORQUE ITTING I D METHOD FOR PRODUCING THE SAME Ori ina iled Feb. 18, 1931 2 Sheets-Sheet 1 April 1935- H. 1... WAISNER 1,998,108

TORQUE TRANSMITTING MEMBER AND METHOD FOR PRODUCING THE SAME Original Filed Feb. 18, 1931 2 Sheets-Sheet 2 Patented Apr. 16 i935 PATENT OF TOUE TRANSMITTING DIEMBER AND METHOD FOR PRODUCING THE poration of lllinois Application February 18, 1931, Serial No. 518,565 Renewed .l 15, 1834 This invention relates to the manufacture and treatment of metals and has particular reference to the manufacture of bar stock of ferrous metals having improved characteristics.

g The usual customary methods for nuiacturlng bar stools oi steel, alloy steels, and a n; lar materials are such that the direction of the h ber fiow is pael to the longitudinal axis oi the bar. In the manufacture of various types of in articles, it is custory to cut the metal either lengthwise or cross=wise oi the bar. Because of s the cuts will. en; 1;" lie either parallel with the fiber or cross-wise thereof.

It is a well known fact that the resistance to is abrasion and the ulate strength of the metal diner depending upon whether the force is applied in the direction of, or at right angles to,

the fiber how. in the former case, the strain is borne by the e of the fibers oi the metal 20 while in the latter the strain must be borne by the weaker flow lines. In the former case the metal exhibits its greatest strength while in the latter it exhibits its minimum strength.

in making torque transmitting members it is 25 convenient and economical to cut the splines,

teeth and the like, lengthwise of the bar, whereby the faces thereof must necessarily lie parallel to the fiber fiow. Under these circumstances the force directed against these portions of the 30 member is at right angles to the fiber flow of the metal and as a result the metal exhibits its minimum strength whereby the portions are relative- 1y easily broken off. In the case oitorque transmitting members such as gears and the like, it

35 becomes necessary, in order to develop suflicient strength, and resistance to wear in the teeth,

to form the blanks through a forging operation to rearrange the fiber fiow. However, the use of forging operations results in a member in which 40 the metal is of variable density whereby satisfactory heat treatment of the member becomes difilcult.

There is also a considerable dlirerence in the machining characteristics of the metal depend- 45 ing upon the relation between the direction of the cut and the direction of the fiber flow, this dlflerence being a maximum when cross-wise and lengthwise cuts are made on the usual type oibarstoclnl- 50 One of the principal objects of my invention is the'provision of torque transmitting members from bar stock wherein the fiber flow is hellcally directed within the bar thereby to produce an object of improved torsional strength, ma-

55 chinability and wear resisting properties, par- 1 w (GE. 2%1593) ticularly in the teeth or transmitting projections. Another object of the invention is the provision of torque transmitting members having terially less susceptibility to distorslon duringv the heat treatment thereof. 5

i have also {it to provide a torque transmit mber wherein the fiber flow thereof is helically directed wit the member to increasethe torsional strength and impact value thereof.

Another object oi the invention is the provision of a torque transmitting member having longitudinal faces wherein the fiber fiow lies at an angle with respect to the faces.

A still further object of the invention is the provision of a ethod for manufacturing toothed torque transmitting members wherein the cost of manufacture is materially reduced. 7

Other objects and attendant advantages will become apparent to those skilled in the art from description and the accompanying drawings, in which- I Figure 1 shows a conventional bar stock section wherein the fiber flow lies parallel to the longitudinal s;

Fig. 2 shows a bar stock section in which the fiber flow lies helically about the longitudinal axis, representing one step in my improved method;

Fig. 3 is a wide elevation of a propeller shaft splined stud end made from bar stock in which the fiber how is hell arr ed;

Fig. 42 is a side view of a bl from which a gear is to be cut;

Fig. 5 is a side view of the gear before the teeth have been cut therein; and

Fig. 6 is a side view of the finished gear.

The invention contemplates, the twisting of bar stock of steel or similar material in order to helically dispose the fiber flow about the longitudinal center of the bar. This permits the forming of longitudinal or transverse slots or projections on the bar in the usual manner without having the fiber flow parallel with the longitudinal surfaces thus formed. Because of the helical direction of the fiber fiow, the transverse 45 slots or projections are cut across the fiber flow so that such formations will have greater strength and greater wearing properties. The amount of this twist may vary considerably depending upon the purpose i'or which the material is to be used. I have in some instances twisted the stock through an angle of 75 per inch and in other cases I'have succeeded in imparting a twist of as much as 375 per inch. l

Referring to the drawings, Fig. 1 shows a'porposition of the fiber fiow after a bar such as that shown in Fig. 1 has been progressively twisted. Fig. 3 shows a stub end made from twisted bar stock similar to that shown in Fig. 2. The numeral I designates an upset head on the end of a bar 8 and indicates the manner in which the usual metal working methods may be employed without disturbing the helical position of the fiber flow. Splines II are formed in the bar through which rotary motion is transmitted to the stub end. It will be seen from the lines 6 that the fiber fiow lies at an angle with respect to the faces II of the splines thereby imparting materially greater torsional strength and higher impact value than would be the case were stock of the nature shown in Fig. 1 used.

Figs. 4, 5, and 6 show the various steps in the formation of a gear. In this instance a blank I3 of suitable length is cut from bar stock of substantially the same diameter as the gear to be formed; the bar having previously been twisted to dispose the grain flow 6 helically about the longitudinal center of the bar. The structure shown in Fig. 5 is then formed from the blank l3 by the usual well known machining operations, after which the teeth [4 are out on the outer surface of the gear as shown in Fig. 6 to provide faces l5 and I6. It will be seen that the grain flow 6 within the teeth l4 lies at an angle with respect to the faces I5 and I6, and that when the faces I5 and I6 are brought against the faces of a cooperating gear the force exerted upon these faces will be directed against the ends of the metal fiber, that is, at an angle with respect to the grain fiow rather than parallel therewith. In forming a gear in this manner from twisted bar stock the forging operations are completely eliminated and a gear having uniform strength results. It will furthermore be seen that by eliminating the forging operation and cutting the gear directly from a twisted blank, a member results in which the metal is of uniform density and which may be heat treated without the dimculties attendant upon variable metal density.

The orientation of the fiber flow may be accomplished by any desired method. In one particular instance I have employed a bar of commercial steel in which the fiber flow lies parallel to the longitudinal axis. I have heated this bar to a temperature near the rolling temperature of the metal and have then imparted rotation to one end of the bar, the other end being held stationary. I believe it advisable to impart the twist to the bar at a temperature near the rolling temperature in order to avoid any possible rupture. This exact temperature will, of course, vary somewhat depending upon the composition of the metal. If desired, the twisting of the bar stock may be accomplished during the rolling process. At this time the metal is at a temperature suitable for the twisting process and such a step may be interposed between various steps of the rolling operation. I have then normalized and annealed the metal and found that the orientation of the fiber flow has not been altered by this treatment. A feature of this invention is, however, the fact that these operations are normally eliminated, thereby reducing the cost of manufacture. Upon machining the bars so treated I have observed that the machinability of the metal has been materially improved.

In order to compare the characteristics of bars in which the fiber flow is parallel to the geometric axis and bars in which the fiber fiow was helically disposed, I have conducted a number of tests in which stub ends made of both types of bars were employed. The treatment of each was identical except for the twisting step, the twisted bar being given a twist of per inch. Both pieces were made from the same bar; were normalized together in the same furnace; were annealed together in the same furnace, and were hardened, and drawn in the same manner and by the same operator. Upon test both articles showed the same Rockwell hardness (R. C. S.). The article made from the metal in which the fiber flow was helically disposed showed noticeably less dimensional changes during the heat treatment, while the torque strength for the twisted article was 1075 foot pounds and the torque strength for the article in which the fiber flow was parallel to the geometric axis was 975 foot pounds. These tests conclusively show that the article made from the steel in which the fiber flow was helically disposed had a. greater torque strength, were less susceptible to distortion and displayed improved machinability,

The use of my invention permits the use of cheaper grades of material in torque members and like articles wherein torsional strength is a material factor. The use of the process materially improves the machinability of the metal and thereby reduces the machining costs.

The cost of producing articles in quantity is reduced because of the fact that fewer of the finished articles are rejected upon inspection because of distortion during the heat treatment thereof. This is probably due to the fact that the twisting operation brings the metal to a more uniform density, increases the density of the metal and brings the fibers thereof in closer proximity.

The invention also serves as an inspection step as any glaring defects in the metalwill be apparent during the twisting operation and rejection may be made at this time. Minor defects of the metal will be cured by twisting the metal as described. Thus the use of the twisting operation avoids the possibility of such defects going unnoticed until final inspection of the bar stock or even until the finished articles have been manufactured. In this manner the number of rejected finished articles is still further reduced whereby the cost of production is also reduced.

A further result of the use of my invention is the fact that when longitudinal forms or shapes are produced the fiber fiow will not lie in a plane parallel to the longitudinal faces but rather at an angle with respect thereto, thereby materially increasing the strength of the article to forces directed at right angles to these longitudinal faces.

The invention is, however, by no means limited to the particular applications herein set forth but will be of value in innumerable other and different uses. For example, my invention may be advantageously employed in the manufacture of line shafts, coiled spring axles, sucker rods, journals, and innumerable other articles of commerce in which desirable characteristics will be imparted to the finished article by helically disposing the grain flow in the bar stock from which they are manufactured.

While I have thus described and illustrated a specific embodiment of my invention I am aware that numerous alterations and changes may be made therein without materially departing from the spirit or the invention and the scope of the appended claims in which- I claim:

1. An article of manufacture comprising a solid torque transmitting member formed from a single piece of metal and wherein a substantial amount of the metal fiber flow is helically directed to a substantial degree throughout the length of said member.

2. An article of manufacture comprising a torque transmitting member of improved torque strength and wearing properties formed from a solid bar and having at least one working face parallelto the longitudinal axis of the bar, the. grain flow being helically arranged in said member and at an angle with respect to said working face.

3. The method of manufacturing a toothed torque transmitting member of metal bar stock which includes forming a solid bar of said metal, helically directing the fiber flow of said metal while substantially at its rolling temperature, and circumferentially and longitudinally cutting the resultant bar to the desired shape, and to form torque transmitting teeth.

4. The method oi? forming a toothed torque transmitting member which includes forming a solid bar of desired diameter in which the grain flow is helically directed, machining the bar to size and shape, and heat treating the same.

5. The method of manufacturing splined stub ends which includes the steps of forming a solid bar of metal, twisting said bar to helically direct the grain flow of said metal, and cutting longitudinal slots in said bar to form teeth therein.

6. The method of forming gears which consists in the steps of forming a solid bar of metal, twisting the bar to helically direct the grain flow, machining the resultant bar to form the gear, and heat treating the same.

7. The method of forming gears which includes machining a solid bar in which the grain flow is heiically directed to shape the gear and form teeth therein, and heat treating said gear.

8. The method of forming toothed torque transmitting members without forging which includes the steps of forming a solid bar of metal in which the grain flow is helically directed and machining the same to shape the member and form teeth therein, and heat treating the same for the purpose of causing the ends of the metal grain to face the working faces of the teeth and to produce a member of uniform density.

. nomica L. WAISNER.

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