US1996439A

US1996439A - Automatic template following profiling tracer

Info

Publication number: US1996439A
Application number: US748903A
Authority: US
Inventors: Robert D Shaw
Original assignee: Pratt and Whitney Co Inc
Current assignee: Pratt and Whitney Co Inc
Priority date: 1934-10-18
Filing date: 1934-10-18
Publication date: 1935-04-02
Anticipated expiration: 1952-04-02

Description

R'. D. sHAw April 2, 1935.

AUTOMATIC TEMPLATE FOLLOWING PROFILING TRACER Filed Oct. 18, 1934 'l VIII/A 711/11//1/ /A lc c . INVENTOR Roe Zl'aw ATTORNEY Patented Apr. 2, 1935 UNITED STATES PATENT 'OFFICE AUTOMATIC TEMPLATE FOLLOWING PROFILING TRACER Application october 1s, 1934, serial No. 748,903

6 Claims.

This invention relates to profiling machines, particularly to an automatic profiling machine controlled and operated by electrical means. More particularly the invention relates to aA template following tracer for a machine such as disclosed in U. S. Patent No. 1,683,581 granted Septer 4, 1928. I

A primary object of the present invention is to improve the construction of the template following tracer mechanism enabling the machine to automatically follow and cut the profile of a generally circular or curved outline.

The present invention constitutes an improve` ment upon the tracer and associated mechanism shown and described in my copending application Serial'No. 717,760 led March 28, 1934, entitled Proling tracer.

A feature of importance in the present irnproved construction is the provision of resilient retaining means for the tracer lever, the resultant force of which may be angularly varied during operation of the machine and while the tracer is following the template being reproduced.

Another feature of importance is that angularly disposed resilient means, preferably in the form of angularly spaced tension springs, are employed to normally hold the tracer lever toward the edge of the template being followed, the tension of one of these springs being adjustable during operation of the machine, cams being employed for that purpose to vary the position of the outer end of the spring.

With the above and other objects in view my invention includes the features of construction and operation set forth in the following specification and illustrated in the accompanying drawing.

In the accompanying drawing annexed hereto and forming Ya part of this specification, I have shown my invention embodied in an automatic profiling machine of the type indicated in the above referred to patent andapplication, but it will be understood that the invention can be otherwise embodied and that the drawing is not to be constructed as defining or limiting the scope of the invention,the claims appended to this specification being relied upon for that purpose.

In the drawing:

Figure 1 is a longitudinal sectional view of the tracer lever, its housing and parts cooperating therewith.

Fig. 2 is an end elevation taken from the left hand end of Fig. 1.

Fig. 3 is an end elevation taken from the right end of Fig. 1 upon the broken line 3 3, and

Fig. '4 is an end elevation of the template and contacting end of the tracer lever shown in several different operative positions. l

In the above mentioned drawing I have shown butone embodiment of the invention which is now deemed preferable, but it is to be understood that changes and modifications may be made within the scope of the appended claims without departing from the spirit of the invention.

Briefly and in its preferred aspect my invention may include the following principal parts: First, a tracer lever mounted for universal oscillation about an intermediate point longitudinally thereof and having a. template following member and contact making and breaking means at opposite ends thereon; second, a member mounted for ro-A tation substantially upon the central line of the tracer lever and having interconnecting means with the template so that this member is forced to rotate as the template is traversed by the tracer; third, a rotatable member adjacent the end of the tracer lever opposite the template and driven in timed relation with the first mentioned rotatable member; fourth, resilient means coupling the second rotatable member and the tracer lever for normally holding the tracer in contact with the template; fifth, a supplemental resilient means disposed at an angle to the first resilient means connecting the second rotatable member and the tracer lever and tending to force the tracer along the outline of the template; sixth, a pivotal arm to which the last mentioned resilient means is attached at its outer end so that oscillation of this arm will increase or decrease the tension of the auxiliary resilient member; and seventh, cams fixed in position for engagement by the extended end of the pivotal arm so that the tension of the auxiliary resilient member may be controlled in different portions of the outline being followed as Vthe tracer engages different. portions of the template.

In the use of the template following tracer disclosed in my copending application it has been found that the forms of outlines satisfactorily followed are limited. Outlines departing to extreme degrees from a circle could not be followed satisfactorily with each of the 'resilient means or tension springs retained inA one adjusted position. At-certain parts of the outline the position of the auxiliary or advancing spring should be changed'or its tension varied. This is for Y the purpose of varying the advancing force.. or

plate. The direction of the resultant force of the two angularly disposed springs acting upon the tracer lever must be adjustable to a limited extent, this being accomplished by varying the tension of one of the springs by means presently to be disclosed. In the present instance the adjustment is eifected upon the auxiliary spring only. By increasing the tension of this spring the tendency'for or ability of the tracer to "advance along the outline of the template is increased.

Referring more in detail to the figures of the drawing, I provide a tracer support Il and tracer lever I I similar generally to those shown and described in Patent No. 1,683,581, this lever I I being mounted for oscillation about an intermediate point as by means ofthe ball and socket bearing I2. At one end oi' this tracer lever II is a template engaging member I l, this end having a disc thereon the diameter of which is chosen to correspond to that of the cutter being used. Adjacent the opposite or rear end of the tracer lever II are the-four pairs of contact making 'and breaking members I4 similar in every way to those shown in Patent No. 1,840,853. At the extreme rear end of the tracer lever ,II opposite the template. contacting end there is provided a mounting or bearing for a rotatable member I5 in the form of a ring or disc to which arev attached the outer ends of tension springs I8 and' II. The inner ends of these springs I8 and I1 are attached in any suitable manner to the extreme from the axis of the tracer lever II by means of their nuts the tension of the springs I5 and I1 and the resilient force urging the tracer lever toward the template may be widely varied. l"I'l'iese springs I6 and I1 act upon the tracer lever II in the same manner as the springs disposed at the template contacting end of the 'tracer in my copending application. h

As shown in Fig. 2 one of the springs, namely spring I6, has its outer end attached tol its screw I8 which is threaded into a bracket 28 secured rigidly to the ring I5. 'I'he other' spring f1, however, is attached by its screw Il to a pivotally mounted lever 2| which may oscillate to increase and decrease the tension of this spring.

The lever 2I may preferably be mounted in a oscillated positions the tension of spring I1 may be controlled throughout the operation and while the tracer I3`traverses the entire periphery of the template M. lIn the present instance the template Mis of ellipsoidal form and the tension of spring I1 is varied in alternate quadrants as the tracer proceeds about the template. 'Ihe cams 24 therefore take the form of arcuate segmerits of approximately 90 each. Innalternate quadrants, therefore, the lever 2| may bear upon tracer lever I I.

the inner periphery of the fixed supporting member 25 and be held in one oscillated position and in the other portions may be engaged by edges of the cams 24 and held in an oscillated position which materially increases the tension of the spring I1.

In order to rotate this ring or disc I5 onwhich the springs I6 and I1 are mounted and therefore rotate the springs to constantly urge the tracer member I3 toward the particular part of the template outline being followed and being cut by the machine, driving means are provided from the front or template following end of the tracer mounting I0. At this end of the tracer mounting I0 is a rotatable member 28 generally similar to the corresponding rotatable member shown in my topending application. 'Ihis member 28 is provided with a radially disposed slot 29 engaging a projection 30 outstanding centrally from Cthe template M as shown and described in my copending application. This rotatable member 28 is provided with gear teeth on its outer periphery which engage a gear 3I on one end of an intermediate shaft 32 suitably supported and extending parallelly to'the tracer mountingk I0. The rear end of this shaft 32 is provided with a gear 23 meshing with gear teeth provided on the rotatable member I5 at the opposite end of the The gearing is so disposed that movements of the rotatable members 28 and I5 at opposite ends of the tracer lever I I are always in exactly the same relative angular or rotative position. 'I'he springs I6 and I1 are, when in operative position and during operation, disposed substantially on the opposite side of the axis of the tra'cer II as the slot 29. An extension of the slot 29 to the opposite side of the ring 28 would intersect the angle between the two springs I6 and I1 which is indicated in Fig. 2.

What I claim is:

1. A template following tracer for profiling machines comprising in combination, a univer- -sally oscillatory tracer lever, oscillation of which controls relative movement between a cutter and work, a member mounted onsaid lever and roltatable about a fixed axis substantially concentric with said lever, means to rotate said member during operation as the tracer traverses the tem-l plate, resilient means normally holding said tracer toward said template in all positions of the tracer relative to the template, the direction of action of said resilient means being adjustable at diiferent portions of the path of movement of the tracer about the template.

2. A template following tracer for. profiling machines comprising in combination, a universally oscillatory tracer lever, oscillation of which .controls relative movement between a cutter and work, a member mounted on said lever and rotatable about a fixed axis, springs mounted on said rotatable member and engaging the tracer lever whereby said tracer lever is held in contact with the template during. operation, means' to rotate said member as the tracer arm traverses the periphery of the template, and means varying\the tension of one of said springs during operation.

3: A template following tracer for proiiling machines comprising in combination, a universally oscillatory tracerl lever, oscillation of which controls relative movement between a cutter and work, a member mounted on said lever and rotatable about a iixed axis, springs mounted on said rotatable member and engaging the tracer lever whereby said tracer lever is .heldin contact with the template during operation, means to rotate said member as the tracer arm traverses the periphery of the template, and a cam adjacent said rotatable member for varying the tension of one of said springs during operation. A

4. A template following tracer for proling machines comprising in combination, a universally oscillatory tracer lever, oscillation of which controls relative movement between a cutter and work, a member mounted on said lever and rotatable about a fixed axis, angularly spaced springs disposed between said rotatable member and the tracer lever whereby said tracer lever is held in contact with the template during operation, means to rotate said member as the tracer arm traverses the periphery of the template, and cam means operative upon one of said springs to vary its tension at predetermined portions of the path of movement of the tracer about the template.

5. A template following tracer for profiling machines comprising in combination, a universally oscillatory tracer lever, oscillation of which controls relative movement between a cutter and work, a member mounted on said lever and rotatable about a tlxed axis, means to lrotate said member during 'operation as the tracer traverses the template and in timed relation therewith, resilient means normally holding said tracer against said template in all positions of the tracer relative to the template, the tension of said resilient means being adjustable at predetermined points in the path of movement of said tracer about said template.

6. A template following tracer for proiiling machines comprising in combination, a universally oscillatory tracer lever, oscillation of which controls relative movement between a cutter and work, a member mounted on said lever and rotatable about a fixed axis, means to rotate said member during operation asthe tracer traverses the template and in timed relation therewith, and angularly spaced resilient members normally holding said tracer against said template in all positions of the tracer relative to the template, one of said resilient means being adjustable at predetermined points of the path of movement of the tracer about the template to vary its tension.

ROBERT D. SHAW.