US2483751A - Stud driving mechanism - Google Patents

Description

6 SheetsSheet 1 INVENTOR r 6 a w W N mm m M w fi m W.

w. B. B RONAN DER STUD DRIVING MECHANISM Oct. 4, 1M9.

Filed Jun-5 23, 1945 Oct. 4, 1949. w. B. BRONANDER 2,483,751

STUD DRIVING MECHANISM Filed June 23, 1945 6 Sheets-Sheet 2 N INVENTQR lVzMeZmZ. 3702mm? Mm wvw g K Get. 4, 1949. w. B. BRONANDER 2,483,751

STUD DRIVING MECHANISM Filed June 23, 1945 e Sheets-Sheet :s

I INVENTOR f/z/ia/m 3 5707747274 t, 4, 1949. -w. B. BRONANDER 2,483,751

STUD DRIVI.NG MECHANISM Filed June 23, I945 e Sheets-Sheet 4 INVENTOR Get 4, 1949.; w. B. BRONANDER 2,483,751

s'ruu DRIVING MECHANISM Filed June 23, 1945 6 Sheets-Sheet 5 I BY ATTORNEY g 1949. w. B. BRONANDER ,4

s'ruu DRIVING MECHANISM Filed June 23, .1945 v a Sheets-Sheet s INVENTOR Patented Oct. 4, 1949 2,483,751 STUD DRIVING MECHANISM Wilhelm Bronander, Montclair, N. J

Original application November 5,1942, Serial No. 464,626, now Patent No. 2,379,878, dated July Divided and this application June 23, 1945, Serial No. 601,147

3 Claims. (01; 74-411) This invention relates to stud driving mechanism and this application is a division of my Patent No. 2,379,878 issued July 10, 1945.

Studs are threaded at both ends and screwed into engine casings, cylinders, etc., and parts are secured to the studs by nuts which are screwed on the outer threaded ends of the studs. Such studs are subjected to heavy loads and tremendous pressures and only studs having the proper size or fit can be utilized.

In the aircraft industry in particular, the proper mating of studs and stud holes is most important. It is essential that the studs be driven in under not less than a certain, predetermined torque, or the studs may shake loose. Moreover, it is absolutely essential that the torque drive does not exceed a predetermined limit as it has been found that if this torque is exceeded, after a cer tain number of hours of actual flight, the studs will fatigue due to strain and will crack. I v Government specifications, for this reason, set minimum and maximum torque limits, but all studs are tested by manually operated torque wrenches. Such operations are difficult to control and sabotage is very difficult to detect.

At the present time it is usual to screw the studs in by hand, using large wrenches having sufiicient leverage to furnish the necessary torque .required to screw the studs in tightly. If the stud is too large it will not screw in to a suflicient extent and must, therefore, be unscrewed and rejected. On the other hand, if the stud is too .small, relative to the size of the thread of the much greater torque effort is required to loosen .the stud and unscrew it than was expended under the predetermined maximum driving efiort.

-The procedure above outlined is laborious, time consuming and expensive and, furthermore, is not productive of the required accuracy in sizing or grading the studs relative to the openings in which they are screwed. I V

This invention has for its salient object to provide efiicient stud driving mechanism so constructed that the studs can be driven in at predetermined minimum and predetermined maximum torque and can be unscrewed and removed if the stud has not been driven in far enough under the predetermined maximum torque drive.

Further objects of the invention will appear 55 from the following specification taken in connection with the drawings which form a part of this application, and in which Fig. 1 is an elevational View of the machine constructed in accordance with the invention and adapted for use in carrying out the method;

Fig. 2 is an elevational view, partly in longitudinal section, of the driving end of the machine shown in Fig. 1;

Fig. 3 is a vertical sectional elevation taken substantially on line 3--3 of Fig. 2, looking in the direction of the arrows;

Fig. 4 is a vertical sectional elevation through the tool head, this view being taken substantially on line i4 of Fig. 5, looking in the direction of the arrows, Fig. 4 being on an enlarged scale;

Fig. 5 is an elevational view, partly in section, taken at right angles to Fig. 4;

Fig. 6 is a diagrammatic view illustrating the neutral position of the clutch and clutch control mechanism;

Fig. '7 is a diagrammatic view similar to Fig. 6

but showing the clutch parts adjusted for low speed maximum torque driving operation;

Fig. 8 is a diagrammatic View similar to Fig. 6 but illustrating the clutch members adjusted for transmitting the drive at high speed and predetermined minimum torque; and

Fig. 9 is a sectional elevation showing a modified form of drive in which the low speed and high speed drives are obtained direct from the motor without the use of two sets of gearing as illustrated in Figs. 1 and 2.

The invention, briefly described, comprises a tool head having a chuck for receiving the stud to be driven, and driving connections between the driving mechanism and the chuck whereby the tool spindle or chuck may be driven in either direction at high speed or low speed. The drive transmitting mechanism between the drive mechanism and the chuck includes drive control means so constructed that minimum torque may be first applied to the chuck and stud carried thereby and if the stud satisfactorily withstands the minimum torque drive. maximum torque may be applied thereto. Suitable testing means is provided whereby the operator can easily and quickly determine whether the stud successfullywithstands the minimum and maximum torque drives.

The drive transmitting mechanism includes a driving clutch connection and a worm drive, so arranged that when the stud encounters predetermined resistance on predetermined minimum or predetermined maximum torque forward drive, the clutch will yield and will limit the drive transa cylinder I 21 formed in the upper end of the tool casing. A suitable fluid is admitted to the cylinder chamber I28 and when this fluid under pressure is admitted to the chamber I28, the piston I is depressed in the cylinder I21 carrying with it the plunger I02. As the plunger is depressed, the collet and collet jaws are forced downwardly in the sleeve 92, the chuck 95 causing the jaws to tightly grip the threaded end 99 of the stud S which has'been previously inserted in the collet jaws in a manner hereinafter described.

Since the drive between the shaft 65 and the hollow shaft 82 is transmitted through a worm gear drive mechanism, when the torque or resistance encountered as the stud S is screwed into the work exceeds a predetermined amount, the stud S can no longer rotate and the worm gear 88 will tend to move longitudinally on a shaft 65.

In order to prevent this movement, the mechanism shown in Fig. 5 is provided. From this figure it will be seen that the shaft 65, which is hollow, has threaded thereinto a stud or rod I38 on which is mounted a Spring I3I which seats in a cup I32 at one end and at its opposite end against adjusting nuts I 33 threaded on the stud I38. The spring tension obtained by the use of the spring I 3| will tend to prevent the relative movement of the gear 88 to the left and axially of the shaft 65 as indicated by the arrow in Fig. 2.

' Drive transmission and control mechanism This mechanism is particularly shown in Figs. 2, 6 and '7. As shown in Fig. 2, the hollow shaft has pinned thereto at I48, a shaft I4I. On the outer end of the shaft MI is mounted on a ball bearing I42, a cap I43 having an arcuate surface I44. A collar I45, cup shaped in cross section, is mounted on the shaft MI and' is held in the desired position by adjustment by means of a nut I48 which is threaded onto the shaft I4I. Springs I41 engage the cup shaped collar I45 and also set in a flanged collar I48 which seats against the inner ball race I59 of the ball bearing 41 and rotates therewith.

The springs I41 are adapted to provide a minimumdriving torque in the following manner.

Since the drive between the shaft 45 and the shaft 51 is transmitted through worm driving mechanism, when the stud S encounters a predetermined resistance, the worm gear 56 will be prevented from rotating, thereby causing the worm gear 55, which is still being driven, to move lineally in the direction of the arrow in Fig. 2. Movement of the worm gear 55 in this direction will tend to cause the shaft 45 to move toward the left, viewing Fig. 2, thus moving the intermediate clutch transmitting plate or disk 48 relative to the driving disk or clutch member 5|, to a sufficient extent to limit the torque transmission to a predetermined setting. In order to permit the stud to be screwed in to the desired extent or with a' minimum torque driving effort, the springs I41 a'reprovided. These springs, as clearly shown in Fig. 2, tend to move the shaft 45 to the right, viewing Fig. 2, thus partially counteracting the tendency of the shaft to move toward the left due to the slowing down or stopping of the worm wheel 56. The springs I41 are so chosen as to accomplish the foregoing result to the desired extent.

This torque yielding or torque limiting action takes place on forward drive only. However, when the drive is in reverse the worm gear 55 will tend to move the shaft 45 to the right, viewing Fig. 2. Thus, the thrust reaction clamps the ill 6 clutch disk 40 to the driving disk 5|, giving practically a positive reverse drive. This is particularly important under a condition encountered when the stud has been driven in under maximum torque but has not been driven far enough into the work. It has been found that after a stud has been driven in under predetermined torque a much greater torque is required to loosen and unscrew the stud. By thus forcing the clutch disk 48 into tight engagement with the driving disk 5| the necessary additional torque effort required to loosen and remove the stud is provided.

The positionof the shaft 45 and the intermediate clutch member 40 carried thereby is determined by a cam I55 carried by a spindle or stud shaft I56 rotatably mounted in a bearing I51 formed'in the bracket or casing 28.

The cam I55 has formed thereon two concave cam surfaces I58 and I59 which are separated by a ridge I68. Furthermore, the outer edges of the concave surfaces I58 and I59 are bordered by ridges |6| and I62.

' The cam I55 is manually controlled by a handle I63. When the cam is positioned as shown in Fig.

' 2, the cap I43 is disposed opposite the concave surface I59 which is so formed that the shaft 45 is positioned to permit the intermediate clutch member 40 to engage the clutch member 5| and thereby transmit the drive from the shaft 29 to the shaft 45 at low speed.

When the handle is moved to shift the cam I55 to the position shown in Fig. 6 in which the ridge I68 engages the cap I43, the shaft 45 will be so positioned as to dispose the intermediate clutch member or driven plate 48 between the clutch members 36 and 5| and thus no drive will be transmitted to the shaft 45.

When the handle and cam I55 have been shifted to the position shown in Fig. 8 in which the cap I43 is disposed opposite the ridge I6I, the shaft 45 will be shifted to the left, thus engaging the intermediate clutch member 40 with the clutch driving member 36, thus transmitting the drive at high speed to the shaft 45. High speed is also transmitted when the cam is shifted to the position shown in Fig. 8 and the cap I43 is disposed in engagement with the ridge Nil.

7 In addition to controlling the position of the driven disk 48 with reference to the driving disks 36 and 5|, the cam and handle also control the passage of pressure fluid to the tool head cylinder chamber I28. This fluid control is fully shown in my Patent No. 2,379,878 above mentioned and forms no part of the present invention and, therefore, need not be further described.

After the minimum torque drive has been transmitted to the tool and the stud has not been driven in too far thereby, as will be hereinafter ex-- plained, further torque or a maximum torque is applied in the following manner. A bell crank lever comprising arms I and I 86 is pivotally mounted, as shown at I81, on the bracket 21. This lever has a downwardly extending lug I88 which is disposed opposite the outer end of a slidable stub shaft I89 positioned in axial alinement with the shaft 45. A spring I 90 engages the outer end of the arm I86 and is adjustable by an eye bolt |9| which extends through the basemember 25 and is engaged by a wing nut I93.

The spring I90 tends to rotate the bell crank lever in an anti-clockwise direction about the axis I81 and this rotation is normally prevented by means of a latch bar I94 which is pivoted at ans-agar 195.130 the outer e'nd'ofthe arm i185 and 'hasat its opposite end .a hook tli95 which is adapted to en'- gage a latch bar I91.

When the bar ltQflJis lifted, :thefspring 1% will rotate the "bell :crank lever :in an anti-clockwise direction, causing the lug :tBBfito :engageth'e outer end .of the shaft M9 and :to pushthis shaft inwardly .against'the outer end-f the-shaft 45,:th11s further resisting'the tendency oftthis shaft toishift tothe "left. and -:discontinue the \drive between :the intermediate clutch :mendber 48 and l'owwsp'eed clutch :disk S'I. In this manner a maximum driving torque is "permitted in driving thestud into the Work before the'drive is :disconnected.

- -In order to unscrew the stud from the work "in case the stud is not the; proper size, a reversing switch R is provided for the motor M. This switch operates in the usual well known manner to reverse the motor and thereby to reverse the drive. .As hereinbefore explained, upon reverse drive the additional torque required to loosen the stud is available due to the action ofithe worm drive which causes the clutch members to be tightly clamped together, giving practically a positive drive.

If desired, instead of having two driving disks, driven at low and high :"speeds through two sets of gears, as shown in thepreceding figures, the high and low speeds can be taken directly from the motor shaft, as shownin Fig.9. In this case the motor will be provided with low and high speed windings. One drivingdisk 269 'is used and the driven disk Zili is shifted into and out of driving relation thereto.

.It will be understood that the control cam for sh'iftingthe shaft 292 will be simplified since the disk 213i need not be shifted .to the left to engage the high speed :disk as in the other embodiment of .the invention.

The operation of the driving mechanismshould be clear from the foregoingspecification rbutethe action of the worm driving connection between the driven shaft and the .tool shaft on -forward and reverse drive may be briefly summarizedas follows. When the stud S on forward-drive .encounters .a predetermined resistance, the worm gear 56 will be prevented from rotating, thereby causing the worm gear which is still being driven to move lineally in the direction of the arrow'in'Fig. 2. This will -tend .to cause the shaft 55 to move to the left, viewin Fig.2, thus moving the intermediate clutch transmitting ,plateor disk til relative to the driving disk or clutch member 55. to a sufficient extent to limit .the torque transmission to a predetermined setting. If the stud is driven in under minimum torque drive to a satisfactory extent and not too far, the arm I94 is raised, thereby permitting the spring rec through the bell crank lever 1'86 to exert pressure on th shaft ifi'itoward the. right, viewing Fig. 2, and provide a maximum torque driving connection. In case the stud under maximum torque drive has not been driven far enough into the work, it 'must'beremoved and'on reverse drive the worm driving connection reacts on the friction drive to clamp the clutch disk 40 tothe driving disk 5 i effecting practically 'a positivereverse drive. As 'hereinbe'foreexplained, this is important since a much greater torque effort is required to loosen and unscrew the stud than the predetermined maximum torque aelforlt which was utilized to-screw the stud.

'Althoughcer'ta'in specific-embodiments of the invention have been particularly shown and described, it v\will be understood that ithe zinvention'iis :capable of :mo'dfi'cation and changes inthe construction. and in the .arrangem'entaof the various cooperating :parts may :be made without departin from-the spirit 'or scope :o'f the invention, as expressed in the following "claims.

What I claim is:

l. a-macti-ine of the character described, at reversible fni'ction driving member, means diordriving said friction: driving member iin opposite directions a-shaftmounted for axial 'movement, coaxial with the :axis of the friction driving member, a ffiiction dr iv'en member mounted on said axially movable shaft and movable-into "and out of :driving engagement with two degreesnof torque transfer with said friction :driving element as the shait :ismoved:axial1y, a ztool driving shaft, means including a worm driving-connection between said axially movable shaft and said :tool driving-shaft,-said worm driving :co'nnecti'on' ing the torque transmitted. bythe friction driving and driven members and ioper-ating fto. clamp said members in tight :driving relation on reverse drive zan'd means coacting withithe :driv-ing connection -:hetween the driving and driven friction n'ien ihers for increasing the torque zload limit to eiiect the second degree of torque transfer to which the :drive will "be limited on. forward drive.

2. In a machine :ofdiheacharacterdescribedpa reversible drive shaft, means for driving said shaft in opposite directions, a friction clutch member driven thereby, a driven shaft mounted for axial movement, a second-clutch member-on-said shaft andmovable into and out of- *eng'agement with said first 'clutch member-withtwo degrees of torquetran'sfer as said shaft is moved axially, a tool shaft, operative driving connections including'a-worm driving connection between said driven shaft-andsaid tool-shaft,--saidworm driving connection reacting on said clutch members to limit the torque transmitted therethrough to a constantpredetermined minimum torque, when the load on thet'ool shaft on forward drive reaches said predetermined limit, and manually-controlled means "associated with said clutch members on forward drive for "increasing the torque driving effort a predetermined maximum torque limit to effect'th'e second degree of torque therefor, sa'idworm dr'rve'r'ea'cting on said clutch-members to .7 limit the torquetransmitted therethrough to said predetermined maximum torque limit when the resistance on the tool'shaft reaches said predetermined limit, .and said worm driving connection on reverse, automatically forcin said clutch members "into tight driving relation, thereby increasing the'torq'ue transmitted to a limit higher than said predetermined maximum.

:3. In a machine of the character described, a reversible drive shaft, meansfor driving said shaft in opposite directions, a friction clutch member driven thereby, a driven shaft mountedfor axial movement, a second clutch member on said shaft and-movable into .and out of engagement with said first, clutch member with two degrees of torquetrans'fer .as said shaft is-moved axially, a ,.tool .shaf-t, operative driving connections incl uding. .a worm drivin connectionzbetweenwsaid driven shaft andsaid tcol' shaft, said worm-driving connection reacting on said clutch members to limit the torque transmitted therethroughfto atconstant predetermined minimum torque, when the :lead .on the tool shaft on forward drive reac'hes said predetermined limit, :and :means associated with said clutch members-won forward drive for increasing the torque driving effort to a predetermined maximum torque limit to efiect the second degree of torque therefor, said worm driving connection reacting on said clutch members to limit the torque transmitted therethrough to said predetermined maximum torque limit when the resistance on the tool shaft reaches said predetermined limit, and said worm driving connection on reverse, automatically forcing said clutch members into tight driving relation, thereby increasing the torque transmitted to a limit higher than said predetermined maximum.

WILHELM B. BRONANDER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,829,249 Von Beulwitz Oct. 27, 1931 2,355,082 Kearney et a1 Aug. 8, 1944 FOREIGN PATENTS Number Country Date 434,766 Germany Jan. 25, 1927 639,103 France Mar. 5, 1928

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