US2796794A - Intermittently variable feed mechanism for forming changeable lead helix - Google Patents

Description

BRUEGGER INTERMITTENTLY VARIABLE FEED MECHANISM FOR June 25, 1957 E.

FORMING CHANGEABLE LEAD HELIX 4 Sheets-Sheet 1 Filed Feb. 23. 1954 %w@&'

ATTORNEYS I INVENTOR. Ernest Bra/eager BY June 25, 1957 E B EGGER 2,796,794

.RU INTERMITTENTLY VARIABLE FEED MECHANISM FOR FORMING CHANGEABLE LEAD HELIX Filed Feb. 23. 1954 4 Sheets-Sheet 2 INVENTOR. F09. 6 Ernesb Bru/eg q'er ATTORNEYS June 25, 1957 E. BRUEGGER 2,796,794

INTERMITTENTLY VARIABLE FEED MECHANISM FOR FORMING CHANGEABLE LEAD HELIX Filed Feb. 23. 1954 4 Sheets-Sheet 3 (O In Fig 4 INVENTOR. Ernesfi Brwe qyer ATTORNEYS June 25, 1957 E. BRUEGGER" 2,796,794

INTERMITTENTLY VARIABLE FEED MECHANISM FOR FORMING CHANGEABLE LEAD HELIX Filed Feb. 25, 1954 4 Sheets-Sheet 4 BY QWJ ATTORNEYS erally of lathe type.

United States Patent INTERMITTENTLY VARIABLE FEED MECHANISM FOR FoRMrNt; CHANGEABLE LEAD HELIX Ernest Bruegger, Massillon, Ohio, assignor to The Gris- .com-Russell Company, Massillon,.0hi0, a corporation of Delaware App c t February 2 5 S r a N 411, 28

16 Claims. (CI. 32-41 The invention relates to apparatus for automatically varying or changing the lead of a lathe lead screw in various helical lathe operations wherein a helix iswound, formed or cut upon a cylinder or the like, and morepartigcularly to an automatic lead reducer in apparatus for winding a helical fin upon a tube orthe 'likej Tubes for certain types of heat exchangers are provided with helical fins which are wrapped or wound around the tubes and joined thereto on a machine gen- In the manufacture of such helical finned tubes, it is necessary 'in certain locations along the length of the tube to provide collars or the like for supporting the tubes or for tying a plurality of such tubes in bundles without collapsing or disturbing the normal fin spacing generally throughout the length of the tubes by the weight of the other-tubes tied in the bundle.

Under present practice this has required stopping of the helical fin applying apparatus at intervals, cutting the fin material being applied, and performing some special operation at alparticular location, to provide for the collar or support, after which the finning operation must be resumed beyond the point where the collar or support is provided.

The present invention contemplates ,the provision of means whereby the lead or spacing of the convol utions of a helix may be changed substantially automatically at any desired point or points along the length thereof Another object is to provide means whereby thewlead or spacing of the convolutionsof a helical fin maybe thus automatically changed at any desired point ,along the length of the tube upon which the ;fin is being wrapped or wound, without stopping the operation of the machine,

and without cutting the fin material being applied to the tube, whereby at desired locations the cohvolutions of the fins maybe located substantially in contact with each other or substantially bunched in a solid mass to act as a support collar upon the tube.

A further object is to provide neehanisgn ofthecharacter referred to in which a normally non-rotatable worm gear is mounted upon the carriage of ghe lathe Iilge machine and engages the lead screw inthe rnannerof alead not for normally advancin-gthe carriage uniiornrly from 'one-e nd of the lathe bed to the other, rneansbeing provided at one 'or more desired locations in the path of the carriage for automatically rotating the worm gear backward to reduce the leadrate,ofthecarriagedhereby th mbin t s n o u ou o thehelix rb r to tme at such point or points.

,Astil'l further object is .toprovide such mechanisrngin' which theworrn gear is normallyiheld againstrotationby a friction clutch, and a I star ,wheeh operatively. connected to the worm gear, is adaptedtoiberotated at a;pre determined point or points in the ,travel .of the carrialge by means of a trippin locatedatsuch point or'p oint s.

Ano h bi p h t n t iq i t RKQY Q 1 uc m sh uism i wh ch th s u ss :i creat el s n ttd t h M ment haf -thr EQQ E QH fiQ and a friction brake is provided upon such gear reduction for normally preventing rotation of the star wheel.

A further object is to provide means for forming a changeable lead helical groove in a tube or the like, and means for guiding the fin material into said groove for forming a changeable lead helical fin corresponding to the helical groove.

A still further object is to provide means tor adjustab'ly mounting the trip pin or pins at any desired point or points along the bed of the machine.

Stated in general terms, the invention comprises a machine, generally of lathe type, having a carriage slidable longitudinally thereon, a continuously rotating leadscrew being journalled in the bed and a lead nut,'in the'form of a normally non-rotatable worm gear, being mounted upon the carriage and engaging the lead screw, the machine having a headstock and tailstock in which a tube or other cylinder is continuously rotated, means being provided upon the carriage for cutting and/or winding a helix upon the cylinder, trip means being provided at any desired point or points upon the bed of the machine for rotating the worm gear backward at such point or points to reduce the lead of the spiral being cut or formed upon the cylinder.

The above and other objects, apparent from the drawings and following description, may be attained, the above described 'difiiculties overcome and the advantages and results obtained, by the apparatus, construction, arrangement and combinations, sub-combinations and parts which comprise the present invention, a preferred embodiment of which, illustrative of the best mode in which applicant has contemplated applying the principle, being set forth in detail in the following description an'd illustrated in the accompanying drawings, in which: i

Fig. l is a side elevation'of an embodiment of the invention comprising apparatus for simultaneously coiling a metal ribbon and applying the same onto a tube in the form of a helical -fin and intermittently bunching the convolutions of the helical fin at spaced points on the tube;

Fig. 2 is a fragmentary, transverse view showing tool heads by means of which the spiral groove is formed in the tube and the metal ribbon is spirally wound therepn;

Fig. 3 is an enlarged, fragmentary front elevation showing a portion of the bed, the carriage, a portion of the lead screw and means for varying the lead of the heliX; Fig. 4 is a fragmentary top plan view of the parts shown in Fig. 3, parts being shown in section;

Fig. 5 is a transverse section taken on the lined- 5,

Fig.6 is a fragmentary elevation of a po-rtion of a tube with helical fin of variable lead shown thereon.

Referring now moreparticularly to the. embodiment of the invention shown in the drawings, in which similar numerals refer to similar partsthroughout, the invention is illustrated as appliedto a machinefor manufacture of finned tubing, of the general type of Dewald Patent No.

2,004,388 dated June 11, 1 935, and more particularly to the form thereof in which a metal ribbon is simultaneouslycoiled and applied toa tube.

For this purpose a machine ofthe lathe type is illustrated, having supports for a bed 10, and atmotor or other source of power (not shown) for driving the headstock spindle 11 through gearing 12. The spindle 111 is geared to a lead screw 13 through a train of gears 14. Two cooperating tool heads 15 and 16 arevrno unted on the carriage 17 and are adjustable toward and from each other in usual manner.

The 'tailstock 18 is adapted to be anchored at the desired point upon the bed'10 by a set screw-19, and a tube to be :finned, as indicated atT, is adaptedto be ,rotatably mounted between the headstock and tailstock roughening roll 23, and the tool head 16 carries the lead rolls 24 and the knurling rolls 25. All of the above parts may be of the general construction as disclosed in said Patent No. 2,004,388.

The variable feed mechanism for varying or reducing the lead is shown in detail in Figs. 3 to inclusive, to which reference is now made. For this purpose the conventional split lead screw nut is replaced by a worm .wheel 26 which is in constant engagement with the lead screw 13 and assumes the function of the conventional lead screw nut.

This worm wheel 26 is mounted upon the shaft 27, located transversely of the bed, and journalled at opposite ends in the brackets 28 and 29 which are shown attached to the front and rear sides respectively of the carriage 17 as by the cap screws 30. The shaft 27 is held against longitudinal movement relative to the carriage by the collars 31 attached to opposite end portions of the shaft as by set screws 32, and contacting the bushings 33 and 34 in the brackets 28 and 29 respectively.

The worm wheel 26 has a free running fit upon the shaft 27, and is arranged to be normally locked upon the shaft by means of the clutch mechanism shown in detail. 1

in Figs. 4 and 5. This clutch mechanism includes the clutch drum member 35, slidably keyed upon the shaft 27, as by the feather key 36, and provided with the friction cone 37 engaged in the conical socket 38 in the adjacent side of the worm wheel 26.

A collar 39 is fixed upon the shaft 27, as by a set i screw 40 and the worm wheel 26 is normally held in contact with said collar, which positions the worm wheel upon the shaft so as to hold it in constant engagement with the lead screw 13. For the purpose of normally holding the clutch cone 37 frictionally engaged with the worm wheel 26, a pressure spring 41 is located upon the shaft 27 between the collar 42 and the clutch member 36.

The collar 42 may be located upon the shaft at any desired position by means of the set screw 43 for placing the desired tension upon the pressure spring 41. The rear end portion of the shaft 26 is provided with the axial bore 44, within which is longitudinally, slidably located the clutch throw out rod 45 which carries the transversely disposed pin 46 at its inner end located through the elongated diametric slots 47 in the shaft 27 and fixed within the radial bore 48 in the hub 49 of the clutch member 35.

A clutch release knob 50 is rotatably mounted upon the outer end of the clutch throw out rod 45, as by the nut 51 and lock nut 52 located upon the threaded outer end portion 53 of said rod. Clutch release show-pins 54 extend inwardly from the release knob 50, and the inner ends thereof are normally received in recesses 55 in the outer end of the shaft 27.

Radial pins 56 may be provided in the release knob 50 to assist in grasping the same in the hand to pull the clutch throw out rod 45 outward in order to disengage the friction cone 37 from the worm wheel.

The knob 50 may be rotated relative to the rod 45 so that the ends of the show-pins 54 will engage the end of the shaft 27 at points spaced from the recess 55, thus holding the clutch released. The only time that this clutch is released by means of the release knob and show-pins as above described is for freewheeling action of the carriage in either direction upon the bed.

A reduction gear box 57 is'mounted upon the bracket 4 28. Within this gear box is located the reduction pinion 58, fixed upon the adjacent end portion of the shaft 27 and mashing with the reduction gear 59. The gear 59 is fixed upon the shaft 60, which is journalled in the gear box 57 and has the braking hub 61 formed integral therewith.

The gears 58 and 59, together with the braking hub 61, are restrained from rotation during the normal lead by pressure of the brake tension screws 62 upon the braking hub 61. These screws are set on the braking hub just tightly enough to overcome the torque tendency produced in the worm wheel nut 26 by revolving action of the lead screw 13, and consequently the entire lead screw reducing mechanism is normally locked against rotation, or has only linear motion along the lead screw 13. The reduction gears 58 and 59 are so computed that when they come into action they will produce a backward rotation of the worm wheel 26 sufiicient to reduce the lead as desired. a

A star wheel 63 .is fixed upon the outer end of the reduction gear shaft 60, on the outside of the gear box 57, as by the set screw 64 located through the hub 65 of the star wheel. A plurality of radially disposed spider trip legs 66, of suitable length and spacing, are fixed in the periphery of the star wheel 63.

An angle gauge rail 67 is attached to the front side of the bed 10, as by screws 68, and extends the full length of the finning. capacity of the lathe. At one or more points along the angle gauge rail 67, where it is desired to reduce the lead, trip means may be mounted upon the rail 67. i

As best shown in Figs. 3 and 5 this trip means may comprise a trip gauge block 69 having the horizontal slot 70, in its rear side for mounting upon the horizontal flange of the angle rail 67, a clamping screw 71 being threaded in a suitable tapped bore 72 in the block for clamping it in adjusted position upon the rail.

A horizontally disposed trip pin 73 is carried by the trip gauge block 69 and adapted to be normally located in the path of the trip legs 66 of the star wheel. This trip pin is located diametrically through the hub 74 of the vertical shaft 75, journalled in the trip gauge block 69, and the inner end 73a of the trip pin is normally held in contact with the trip pin stop stud 76 by means of the trip pin return spring 77, which is connected to the inner end portion 73a of the trip pin and to the trip gauge block 69 as by the screw 78. v

With the carriage 17 moving along the bed 10 from left to right, as viewed in Figs. 1 and 3, when one of the trip legs 66 of the star wheel 63 engages the trip pin 73 in a wiping action, additional torque is transmitted to the reducing gears 58 and 59 and braking hub 61, overcoming the torque resistanceset up by the tension screws 62, causing a backward or counter-clockwise rotation of the shaft 27 and worm wheel 26 as viewed in Fig. 3.

This backward rotation of the worm wheel nut 26 subtracts from the normal lead tendency of the lead screw 13, producing a correspondingly reduced lead in the helix being formed by the lathe-like machine.

In the operation of the machine illustrated, for applying a metal ribbon R to a tube T in a spiral or helical chine by the knurling rolls 25, as disclosed in Dewald Patent No. 2,004,388, above referred to, forming a spiral fin R with relatively wide spacingv at normal lead' as under conventional practice.

At thepoint or points 'where the trip fingers 73 are locatedlin thepath of the trip legs upon the star wheel 63, thelead will be automatically reduced by backward 'rotation of the worm gear nut 26 upon the lead screw,

and as shown at R in Figs; 1 and 6, the lead maybe reduced to approximately fin thickness during the time that the worm wheel is being rotated backwardly, producing a substantially solid fin block or collar at this point, as shown.

The length of this reduced lead may be determined by shortening or lengthening the trip legs 66 of the star wheel as desired. As the star wheel moves out of contact with the trip finger 73, the rotation of the worm wheel 26 will be stopped and the worm wheel will again be locked against rotation and the machine will resume normal operation with normal lead, continuing to apply the normally wide spaced fin upon the tube, as indicated at R in Fig. 6.

Although the invention is illustrated and described as applied to a particular type of machine for the manufacture of finned tubing, it should be understood that the variable feed mechanism for varying the lead of a lathe lead screw is applicable to various helical lathe operations wherein it may be desirable to change the lead, whether it be in the wrapping of fins, winding of wire springs, cutting threads, or machining a changeable lead helix on a cylinder, either straight or tapered, which would be adaptable to standard lathe practice.

In the foregoing description, certain terms have been used for brevity, clearness and understanding, but no unnecessary limitations are to be implied therefrom beyond the requirements of the prior art, because such words are used for descriptive purposes herein and are intended to be broadly construed.

Moreover, the embodiments of the improved construction illustrated and described herein are by way of example, and the scope of the present invention is not limited to the exact details of construction.

Having now described the invention or discovery, the

construction, the operation, and use of preferred embodiments thereof, .and the advantageous new and useful results obtained thereby; the new and useful construction, and reasonable mechanical equivalents thereof obvious to those skilled in the art, .are set forth in the appended claims.

I claim:

1. A machine of the lathe type, comprising a bed, a carriage movable longitudinally upon the bed, a lead screw journalled in the bed, means for rotating the lead screw, a normally stationary worm wheel on the carriage and engaging the lead screw for moving the carriage longitudinally at a uniform speed, and means located at predetermined points in the path of the carriage for intermittently rotating the worm wheel to vary the speed of movement of the carriage.

2. A machine of the lathe type, comprising a bed, a carriage movable longitudinally upon the bed, a lead screw journalled in the bed, means for rotating the lead screw, a normally stationary worm wheel on the carriage and engaging the lead screw for moving the carriage longitudinally at a uniform speed, and means located at predetermined points in the path of the carriage for intermittently rotating the worm wheel backward to reduce the speed of movement of the carriage.

3. A machine of the lathe type, comprising a bed, means for supporting a cylinder upon the bed, a carriage movable longitudinally upon the bed, a tool upon the carriage, means for rotating the cylinder with respect to the tool, a lead screw journalled in the bed, means for rotating the lead screw, a normally stationary worm wheel on the carriage and engaging the lead screw for moving the car-riage longitudinally for causing the too] to form a helix upon the cylinder, and means located at predetermined points in the path of the carriage for intermittently rotating the worm wheel to vary the lead of the helix.

4. A machine of the lathe type, comprising a bed, means for supporting a cylinder upon the bed, a carriage movable longitudinally upon the bed, a tool upon the carriage, means for rotating the cylinder with respect to the tool, a lead screw journalled in the bed, means for form a helix upon the cylinder, and means located at predetermined points in the path of the carriage for in termittently rotating the worm wheel backward to reduce the lead of the helix.

5. A machine of the lathe type, comprising a bed, a carriage movable longitudinally upon the bed, a lead screw journalled in the bed, means for rotating the lead screw, a transversely disposed shaft -journalled on the carriage, means normally preventing rotation of said shaft, a worm wheel mounted upon the shaft and engaging the lead screw for moving the carriage longitudinally at a uniform speed, and means located in the path of the shaft for rotating said shaftat a predetermined point to vary the speed of movement of the carriage.

6. A machine of the lathe type, comprising a bed, a carriage movable longitudinally upon the bed, a lead screw journalled in the bed, means for rotating the lead screw, a transversely disposed shaft journalled on the carriage, means normally preventing rotation of said shaft, a worm wheel mounted .upon the shaft and engaging the lead screw for moving the carriage longitudinally at a uniform speed, and means located in the path of the shaft for rotating said shaft backward at a predetermined point toreduce thespeed of movement of the carriage.

7.-A machine of the lathe type, comprising a bed, a

carriage movable longitudinally upon the bed, a lead screw journalledin the bed, means for rotating the lead screw, a transversely disposed shaft journalled on .the carriage, means lnormally preventing rotation of said shaft, a worm wheel mounted upon the shaft and engaging the lead screw for moving the carriage longitudinally at a uniform speed, astar wheel operatively connected tosaid shaft, and a trip pin located at a predetermined point-in the pathof the star wheel for rotating said shaft to vary .the speed of. movement of the carriage.

.8. A machine of the lathe .type, comprising a bed, a

carriage movable longitudinally upon the bed, a lead screw journalled in the bed, means for rotating the lead screw, a transversely disposed shaft journalled on the carriage, means normally preventing rotation of said shaft,

a worm Wheel mounted upon the shaft and engaging the lead screw for moving the carriage longitudinally at a uniform speed, a star wheel operatively connected to said shaft, and a trip pin located at a predetermined point in the path of the star wheel for rotating said shaft backward to reduce the speed of movement of the carriage.

9. A machine of the lathe type, comprising a bed, a carriage movable longitudinally upon the bed, a lead screw journalled in the bed, means for rotating the lead screw, a transversely disposed shaft journalled on the carriage, reduction gearing operatively connected to said shaft, brake means in the reduction gearing for normally preventing rotation of the shaft, a worm wheel mounted upon the shaft and engaging the lead screw for moving the carriage longitudinally at a uniform speed, and means located in the path of the shaft for rotating the shaft at a predetermined point to vary the speed of movement of the carriage.

10. A machine of the lathe type, comprising a bed, a carriage movable longitudinally upon the bed, a lead screw journalled in the bed, means for rotating the lead screw, a transversely disposed shaft journalled on the carriage, reduction gearing operatively connected to said shaft, brake means in the reduction gearing for normally preventing rotation of the shaft, a worm wheel mounted upon the shaft and engaging the lead screw for moving the carriage longitudinally at a uniform speed, a star wheel operatively connected to said reduction gearing, and a trip pin located at a predetermined point in the path of the star wheel for rotating said shaft to vary the speed of movement of the carriage.

.car'riage movable longitudinally upon the bed, a lead screw journalled in the bed, means for rotating the lead screw, a transversely disposed shaft 'journalled on the carriage, reduction gearing operatively connected to said shaft, brake means in the reduction gearing for normally preventing rotation of the shaft, a worm wheel rotatable upon the shaft, a clutch normally locking the worm wheel upon the shaft, means for releasing the clutch to permit free wheeling movement of the carriage in either direction upon the bed, the worm wheel engaging the lead screw for moving the carriage longitudinally at a uniform speed, and means located in the path of the shaft for rotating the shaft at a predetermined point to vary the speed of movement of the carriage.

12. A machine of the lathe type, comprising a bed, a carriage movable longitudinally upon the bed, a lead screw journalled in the bed, means for rotating the lead screw, a transversely disposed shaft journalled on 'the carriage, reduction'gearing operatively connected to said shaft, brake means in the reduction gearing for normally preventing rotation of the shaft, a worm Wheel rotatable upon the shaft, a clutch normally locking the worm wheel uponthe shaft, means for releasing the clutch to permit free wheeling movement of the carriage in either direction upon the bed, the worm wheel engaging the lead screw for moving the carriage longitudinally at a uniform speed, a star wheel operatively connected. to said reduction gearing, and a trip pin located at a predetermined point in the path of the star wheel to vary the speed of movement of the carriage.

13. A machine of the lathe type, comprising a bed, a carriage movable longitudinally upon the bed, a lead screw journalled in the bed, means for rotating the lead screw, a normally stationary worm wheel on the carriage and engaging the lead screw for moving the carriage longitudinally at a uniform speed, a star wheel operatively connected to said worm wheel, and trip pins located at predetermined points in the path of the star wheel for intermittently rotating the worm wheel to vary the speed of movement of the carriage.

'14. A machine of the lathe type, comprising a bed, a carriage movable longitudinally upon the bed, a lead screw journalled in the bed, means for rotating the lead screw, a normally stationary worm wheel on the carriage and engaging the lead screw for moving the carriage longitudinally at a uniform speed, a star wheel operatively connected to said worm wheel, and trip pins located at predetermined points in the path of the star wheel for intermittently rotating the worm wheel backward to reduce the speed'of movement of the carriage.

15. A machine of the lathe type, comprising a bed, means for supporting a cylinder upon the bed, a carriage movable longitudinally upon the bed, a tool upon the carriage, means for rotating the cylinder with respect to the tool, a lead screw journalled in the bed, means for rotating the lead screw, a normally stationary worm wheel on the carriage and engaging the lead screw for moving the carriage longitudinally for causing the tool to form a helix upon the cylinder, a star wheel operatively connected to said worm wheel, and trip pins located at predetermined points in the path of the star wheel for intermittently rotating the worm wheel to vary the lead of the helix.

16. A machine of the lathe type, comprising a bed, a carriage movable longitudinally upon the bed, a lead screw journalled in the bed, means for rotating the lead screw, a normally stationary worm wheel on the carriage and engaging the lead screw for moving the carriage longitudinally at a uniform speed, and cooperating means on the carriage and at predetermined points in the path of the carriage for rotating the worm wheel to vary the speed of movement of thecarriage.

References Cited in the file of this patent UNITED STATES PATENTS 398,871 Wersley Mar. 5, 1889 1,863,553 Berg June 14, 1932 2,035,283 Schroeder Mar. 24, 1936

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