US2833167A - Drilling machine - Google Patents

Description

May 6, 1958 F. H. MUELLER DRILLING MACHINE Filed DBO. 13, 1955 8 Sheets-Sheet 1 May 6, 1958 F. H. MUE-LL'ER DRILLING MACHINE 8 Sheets-Sheet 2 Filed Dec. 13. 1955 I UQFEED all T INVENTOR FRA/VK H. MUELLE? ATTORNEYS May 6, 1958 A F. H. MUELLER 2,833,167

DRILLING MACHINE v Filed Deo. 13, 1955 8 sheets-sheet s INVENTOR FRANK h'. MUELLER ATTORNEYS F. H. MUELLER 2,833,167

DRILLING MACHINE 8 Sheets-Sheet 4 m a U M H. i@ .Bv @Q m NN wg f NQ vh. W- vm. om. KS mm2., v o. om. E EEU May 6, 1958 Filed Deo. 1s, 1955 May 6, 1958 F. H. MU ELLER DRILLING MACHINE 8 Sheets-Sheet 5 Filed Dec. 13, 1955 May 6, 1958 F. H. MuELLl-:R 2,833,167

DRILLING MACHINE Filed nee. 15, 1955 s sheets-sheet e INVENTOR FRA/Vl( H. MUELLER ATTORNEYS 1 May 6, 1958 F. H. MUELLER DRILLING MACHINE 8 Sheets-Sheet 7 Filed D60. 13, 1955 INVENTOR FRA lvl( H. Mug/ L ER ATTORNEYS May 6, 1958 F. H. MUELLER 2,833,167

DRILLING MACHINE Filed Dec. 13, 1955 8 Sheets-Sheet 8 INVENTOR FRA/VK h'. MUELLE? nnrLLnvG MACHINE Frank H. Mueller, Decatur, Ill., assignor to Mueller Co., Decatur, Ill., a corporation of Illinois Application December 13, 1955, Serial No. 552,886

26 Claims. (Cl. 77-42) This invention relates to machines for drilling or tapping mains and pipes without escape of fluid pressure therefrom, and more particularly pertains to improvements in drilling machines of the type disclosed in U. S.

Patents Nos. 1,956,129, 2,470,044, and 2,646,699. p

Drilling machines of the type disclosed in the foregoing patents are provided with a pressure-tight housing completely enclosing a boring bar that usually is driven by power but can be rotated by hand. The machines have lfeed mechanism for advancing the boring bar, and the tool carried thereby, and are also equipped with an automatic drive for the feed mechanism to advance the bar at a rate appropriate for a cutting operation. The automatic drive includes a clutch device which, upon its disengagement, permits hand advance of the boring bar by the rotation of a crank handle connected to the feed mechanism. Advance of the boring bar by hand usually is at a much faster rate than that effected by the automatic drive in order to obtain rapid advance of the cutting tool from a fully retracted position into engagement with the work, and rapid retraction from the work on completion of a cutting operation.

Since the boring bar of drilling machines of the type under consideration is completely enclosed, there arises the problem of determining the axial position of the boring bar at all times. 'Machines of the foregoing type are employed in many instances for drilling or tapping operations on mains and pipes that are under high pressure, and in such an operation it will be seen that the feed mechanism and the automatic drive therefor will remain under a heavy load after a hole has been cut into the pipe, because further advance of the boring bar is resisted by the high fluid pressure in the main or pipe. Thus, there is no obvious indication to an operator of the machine that the drilling or tapping operation has been completed. ln some instances, this disadvantage, particularly when operating on a pipe of relatively small diameter, has resulted in the operator neglecting to shut off the power to the machine so that the boring bar continues to advance and cuts a hole in the opposite side of the main. Unless such a dual cut is intended and the appropriate apparatus provided therefor, the second cut could have disastrous effects.

lt thus will be seen that it would be highly advantageous to provide means in a machine of the type under consideration for continuously indicating the extent of advance of the boring bar from a fully retracted position. lt is, therefore, an object of this invention to provide such a universal travel indicator that is relatively simple, accurate in operation, involves no change-speed mechanism for compensating for the differences between automatic and hand rates of advance, and requires no adjusti mensions.

2,833,167 Patented May 6, 1958 preset feed mechanism with means for indicating the predetermined extent of advance of the boring bar set into such feed mechanism, and to so construct the indicator and the present feed mechanism that the indicator will be returned to a zero indication after the boring bar has advanced through'the predetermined distance.

When a machine of the type under consideration is equipped with a lpreset. feedy mechanism operating to disengage a clutch device in the automatic drive for the feed mechanism, it will be seen, as pointed out above, that in many instances the feed mechanism and its automatic drive will be' under a considerable load at the time that the clutch device is disengaged. Disengagement of a clutch device while under load presents no problem when such device is of the friction type. Drilling machines of the type under consideration, however, require the transmission of considerable power through the automatic drive in order to advance the boring bar, even after a hole has been cut in a high pressure main. Obviously, it is highly desirable to keep the housing enclosing the automatic drive within reasonable size limits, but a friction type clutch capable of transmitting the necessary power through the automatic drive must, of necessity, be so large that it cannot be housed within a drilling machine housing of reasonable and practical di- Consequently, a positively-engageable clutch device must be used to transmit the power through the automatic drive.

Disengagement of a positively-engageable clutch device under load, however, gives rise to an immediate difticulty. It will be seen that if a positively-engageable clutch device (which includes such mechanisms as slidably-disengageable meshing gears, the two parts of a dental or jaw clutch, a dive key disengageable from a slot or groove in another part, and the like) is disengaged under load, metal will be chipped or shaved from the disengaging parts at the moment of disengagement. The consequent result will be that the positively-engageable clutch device will be damaged practically beyond repair after only a few disengagements while under load. Furthermore, it requires excessive force to disengage a positively-engageable clutch device under load.

Consequently, it is also an object of this invention to provide a mechanism for automatically relieving the load on a power train, which includes a positively-engageable clutch device, during the disengagement ,-f such device to thereby permit disengagement of clutch device without any load thereon, and, consequently, with no damage thereto. lt is another object to so interconnect the load-relieving mechanism and the clutch device that the load is relieved prior to any disengaging movement of the device so that the force necessary to effect disengagement is minimized.

Other objects and advantages of the invention will become apparent from the following description and accompanying drawings in which:

Figure l is a side View, partially in longitudinal section, of a drilling machine embodying this invention;

Figure 2 is an end view of the machine shown in Figure l and taken from the right-hand end of the latter figure; i

Figure 3 is an enlarged, fragmentary view of the right-hand portion of Figure 1;

Figure 4 is an enlarged,"'fragmentary, sectional View taken substantially on lines4-4 of Figure 2;

Figure 5 is an enlarged;d fragmentary, sectional view taken substantially onlines S-,5 of Figure 2;

Figure 6 is -an enlarged, fragmentary side view taken substantially on lines 6-6 of Figure 1, but with parts of the housings being broken away to illustrate details;

Figure 7 is an enlarged, sectional view taken substantially on lines 7-7 of Figure 1;

Figure 8A is a reduced sectional View taken substantially on lines S-8 of Figure 3;

Figure 9 is'a reduced sectional view taken on lines 9-'9 of Figure 3;

Figure 10 is a sectional view taken substantially on lines 10-10 of Figure 3;

Figure `11 is a fragmentary; sectional view taken substantially on lines 11-p-11 of Figure 3;

Figure 12 is a fragmentary, sectional view taken substantially on lines 12-12 of Figure 6;

Figure 13 is an enlarged sectional view taken substantially on lines 13-13 of Figure 6;

Figure 14 is an enlarged, fragmentary, View, with parts being omitted for purposes of clarity, taken substantially on lines 14-14 of Figure 3;

Figure 15 is a view corresponding to Figure `14 but illustrating a different position of the parts;

Figure 16 is a fragmentary, sectional view taken on lines 16-16 of Figure 14;

Figure 17 is a perspective view of the key shown in Figures 14 and 15;

Figure 18 `is an enlarged, fragmentary view of a portion of Figure 3;

Figure 19 is an enlarged, fragmentary sectional view taken substantially on lines 19--19 of Figure 18;

Figure 20 is an enlarged, fragmentary view of a portion of the left-hand side of Figure 1.

Referring now to Figures 1 and 3 of the drawings, there is shown a drilling machine embodying this invention having a barrel provided with a `bottom ange 32 forming the top wall of a lower gear housing 34. The

housing 34 has a removable lower wall 36 having a tubular bearing and guiding extension 38, which is aligned with the barrel 30 and provided with a circumferential ange at its extremity for bolting the machinerin the usual manner to one end of a valve (not shown). At its upper end, the barrel is provided with a plate-like eccentric circumferential ange 42 which, `in conjunction with an inverted bowl-like top cap 44 bolted thereto, constitutes an upper gear housing 46 having a lifting handle 48.

Journaled in bushings 50 and 52 in the upper and lower ends, respectively, of the barrel 30 is a drive tube 54, the upper and lower ends of which project, respectively, into the upper and lower housings 46 and 34. A pair of gears S6 and 58 is secured `by a key 60 (Figures 3 and 10) to the upper end of the tube S4 within the housing 46. Fixed, as by a key 62, to the lower end` of the drive tube 54 and having its hub bearing against a thrust washer 64 interposed between the lower end of the drive tube and the lower wall 36 of the lower housing 34, is a beveled gear 66 engaged by a pinion gear 68 fixed to a driving stub shaft 70 journaled in a bearing 72 fixed in a side Wall of the housing 34. The stub shaft 70 may be suitably driven by an appropriate motor (not shown).

Received in the drive tube 54 is a hollow `boring bar 74, the upper portion of which has a close sliding t in the drive tube and is splined thereto for rotation thereby and axial movement relative thereto by a pair of keys 76 secured to the bar and slidable in diametrically opposite 'interior longitudinal grooves or keyways'77 (Figures 9 and `111) :extending thelength of the drive tube 54. Be-

neath its upper portion the boring bar 74, for the .purpose Q4, of reducing friction, is externally reduced so that a downwardly facing shoulder 78 (Figures 3 and 4) exists. The lower reduced portion of the boring bar 74 is journaled in a sleeve bearing 80 in the tubular extension 38 of the lower housing 34. The extension 38 preferably is provided with an upper oil seal in the form of an O-ring 82 and also with a lower appropriate pressure seal in the form of a stuing box 84. The lower end of the boring bar 74 is closed and provided with a socket 36 for the reception of a tool (not shown). The upper interior portic-u the boring bar 74 is enlarged to provide a shoulder 33 (Figures 3 and 4) which supports an inwardly overhanging abutment ring against which is seated a coaxial feed nut 92. The nut 92 is fixed against rotation relative f' to the bar 74 by keys 94 and fixed against axial movement relative to the bar by a retaining ring 96 threaded into the upper end of the boring bar and locked in place -by set screws 98 (Figure 3) bearing against the upper end of the nut 92.

A hollow feed screw 100 is engaged within the nut 92 and depends coaxially within the boring bar `74. The upper end of the screw 100 has an enlarged, Unthreaded extension 102 which extends through the upper gear housing 46 and projects through, and is journaled in a sleeve bearing 104 supported by, the top cap 44. The projecting outer end of the screw extension 102 has a retaining washer 106 pinned thereto and bearing against a thrust washer 108 mounted against the outer side of the cap 44. Outwardly beyond the retaining washer 106, the screw extension 102 terminates in a squared or otherwise noncircularly formed outer end 110 for reception in the complementary socket 112 of a crank handle 114. Within the gear housing 46 the screw extension 102 has a gear 116 keyed thereto with the gear hub engaging an anti-friction thrust bearing 118 interposed between the gear 116 and a thrust collar 120 xed to the upper wall of the cap 44. It thus will be seen that the feed screw 100 is fixed against axial displacement by the gear 116 and the retaining washer 106.

The feed nut 92 and the feed screw 100 constitute the feed mechanism of the machine for advancing the boring bar 74 on relative rotation between the nut and screw. In a machine of the type under consideration designed, for example, to make a cut 6 inches in diameter into a main, the length of the barrel 30, the boring vbar 74, and the feed screw 100 may be such as to permit the boring bar to have an overall travel, i. e., from its fully retracted position shown in Figures l, 3, and 4 of the drawings to a fully extended position, of about 24 inches. In such a machine the pitch of the feed screw threads is usually such that one complete revolution of the screw 100 rela tive to the feed nut 92 moves the boring bar 74 axially one-tenth of an inch.

An `axtally-shiftable countershaft 122 is journaled in a cap bearing 124 mounted in the flange 42 constituting the lower wall vof the upper housing 46 and in a sleeve bearing 126 mounted in the cap 44, in laterally spaced, parallel relation to the feed screw 100. The upper end of the countershaft 122 projects out of the housing 46 and has an operating knob 128 pinned thereto. Stacked on the countershaft v122 in the following order and held against axial movement between the cap bearing 124 and the sleeve bearing 126 are: a spacer washer 130, a spacer washer 131 having a pair of gears 132 and 134 rotatably journaled thereon'and pinned together for rotation as a unit, a gear 136 selectively connectable and disconnectable with the countershaft 122 for rotation therewith or relative thereto, the bearing portion or hub 138 of a rocker arm 140, a spacer washer 142, a gear 144 keyed to the countershaft 122 for rotation therewith by special means later described, and a cam sleeve 146 journaled on the countershaft 122.

The gear 144 is in constant meshing engagement with the gear 116 on the feed screw 100 while the gear 136 is in constant ineshing engagement with the gear 56 on the drive tube 54. Consequently, when the gear 136 rotates with the countershaft 122, the gears 56 'and 136, the countershaft 122, and the gears 144 and 116 form a power train that constitutes an automatic drive for the feed mechanism. The ratios of the gears 56, 136, 144, and 116 in the automatic drive are such that, when the gear 136 is fixed against rotation to the countershaft 122, 'rotation of the drive tube 54 drives the feed screw 100 at a slightly greater rate of rotation than the feed nut 92 to advance the boring bar 74 at an appropriate rate for cutting a main. Thus, for example, the gearing ratios for the automatic drive may be such as to cause the boring bar 74 to advance one-tenth of an inch on 20 revolutions thereof.

The automatic drive is rendered operative or inoperative by connecting or disconnecting the gear 136 to or from the countershaft 122 by a p-ositively-engageable clutch mechanism. For this purpose the countershaft 122 has a longitudinally-extending slot 148 (Figures 3 and ll) in which is secured,V as by a transverse pin 150, the base or foot portion of a Ispring key 152, normally termed a dive key, which is received with sliding clearance in the slot. The head of the key 152 is urged by its spring shank to project out of the slot 148 for engagement within a longitudinal groove 154 in the interior of the hub of the gear 136. The key 152 is engaged and disengaged with the gear 136 by axial movement of the countershaft 122 which may be shifted manually by the knob 128. Thus, when the countershaft 122 is in the axial position shown in Figure 3, the key 152 projects into the groove 154 in the gear 136 so as to tix the latter against rotation to the countershaft, but when the latter is shifted to the left, an angular face 156 on the key, which bears against the edge of the aperture in the washer 131, cams the key head back into the slot 148 and out of engagement with the gear 136.

In this latter de-clutched or hand feed position, manual rotation of the feed screw 100, by the crank handle 114, when the drive tube 54 and, consequently, the nut 92 are at rest, rotates the -feed screw at a rate fast enough to rather rapidly thread the nut 92 therealong for a fast advance or retraction of the boring bar 74. The knob 128 also may be provided with a lsquared end 158 for the reception of the crank handle 114 so that the latter may be applied either to the countershaft 122 or the feed screw extension 102 for manual feed. For the purpose of yieldably retaining the countershaft 122 in either of its two axial positions, it is provided with spaced, circumferential grooves 160 and 162 for the reception of a spring-pressed ball detent 164 mounted in the cam sleeve 146.

A universal boring bar travel indicator embodying this invention includes a conventional rotatable counter 166 (Figures 4, 6, and 7), set to register zero in the fully retracted position of the boring bar 74 and designed to register the extent of advance of the latter from such position in inches and tenths of an inch. The counter 166 is mounted in 'a housing 168 secured, as by welding, to the barrel and the underside of the flange 42 constituting the bottom of the housing 46 and is protected from damage or abuse by a detachable cover 170 having a clear plastic window 172 (Fig. 7) therein registering with the face of the counter. The counter 166 is `driven by a differential gearing arrangement, best shown in Figures 4, 6, land 10, which drives the counter at the differential rate of rotation between the feed nut 92 and the feed screw 100.

For this purpose, a counter drive shaft 174, disposed in spaced parallel relation to the countershaft 122 and the feed screw 100, has one end thereof journaled in a cap bearing 176 mounted in the gear housing cap 44 and the other end thereof journaled in and projecting out of a tubular bearing 178 mounted in the flange 42. The outer end of the shaft 174 is pinned to the stem 180 of thev 6 counter 166. A carrier 182for a ring gear 184 has'a gear 186 fixedV thereto and is journaled for rotation ona tubular extension of a planetary gear carrier 188 which is coaxially mounted on and pinned to the shaft 174. Afsun gear 19t1concentn'c with the ring gear 184 is carriedby a sleeve extension of another gear 192 which is journaled for rotation on Va bushing 194 mounted on the shaft 174; nter-posed between the sun gear 190 and the ring gear 184 and meshing with both are a plurality of planetary gears 196 carried by the planetary gear carrier 188. Thegear i 1.86 constantly meshes with the gear 58 on the drive tube 54, while the gear 192 constantly meshes with the gear 144 on the countershaft 122. The ratios between the gears 5S and 186, and the gears 144 and 192 are proportioned so that the respective rates of rotation of the ring gear and sun gear 190 are directly proportional to the rates of rotation of the feed nut 92 and feed screw 100.` Consequently, the planetary gear carrier 188 land the shaft 174 rotate at a rate proportional to the differential rate of rotation between the feed nut 92 and the feed screw 100.

Thus, it will be seen that when the boring bar 74 is advanced by either automatic or manual feed, the counter 166 will be driven at a rate directly proportional to such differential rate. The counter 166 is internally geared or constructed to register the number of revolutions of the shaft 174 in terms of inches and tenths of an inch of boring bar advance.

The machine also embodies a preset feed mechanism which` can be adjusted so that when the machine is in automatic feed and the boring bar 74 advances a predetermined distance from any axial position of such bar, the automatic drive will be disengaged and stop further advance of the boring bar. For this purpose the preset feed mechanism includes means for shifting the countershaft 122 from its automatic feed to its hand feed position. This shifting means includes the cam. sleeve 146 which is journaled on the countershaft 122 and has one end thereofcounterbored to form a shoulder 198 (Figures 3, 5, 18, and 19) provided with diametrically opposite, V-shaped cam grooves 200 within which ride the opposite endsl of a pin 202 extending diametrically.

through the shaft 122 when the latter is in its automatic feed position. ,'When the cam sleeve 146 is free to rotate, the camming action between the projecting ends of the pin 202 and the sides of the c am grooves 200 will be ineffective to exert axial forces between the vcam sleeve and the countershaft 122. If the cam sleeve 146 is restrained against rotation, however, it will be seen that the projecting ends of the cam pin 202 will ride up the side walls of the cam grooves 200 and force the countershaft 122 .to shift to the left from its automatic feed to its hand feed position. In suchlatter position of the countershaft 122, the projecting ends of the cam pin 202. clear the shoulder 198 in the cam sleeve 146 so that the countershaft can rotate freely relative to the cam sleeve and enable` operation of the manual feed. f

The apparatus for arresting rotation of the cam sleeve 146 constitutes thesettable part of the preset feed mechanism, and includes an axially-shiftable adjustable shaft 204 (Figures 5 and 6) disposed in parallel, spaced relation to the 'feed screw 100, the countershaft 122, and the shaft 174. The opposite ends of the shaft 204 are journaled in and project through tubular bearings 206 secured in the cap 44 and flange 42 of the gear housing 46. A gear 208 is pinned on the shaft 204 and can be moved into or out of mesh with the gear V132 journaled on the countershaft 122 by axial shiftingof the yshaftV 204. As is shown in the drawings, movement of the shaft 204 to the left, as by a knurled adjustment knob 210 secured on its projecting end, moves the gear 208 out yof mesh with the gear 132. The gear 134, which is pinned to the gear 132, is driven by a gear 212 pinned to-the counter drive shaft 174, as shown in Figure 13.

Thus, rthe shaft204 maybe rotated by the shaft 174, at

7 a rate proportional to the rate of advance of the boring bar` 74. Because of space limitations, later described more in detail, it is desirable for the shaft 204 to rotate at arate considerably'less than that of the shaft 174. For such a reduction drive, the gear 212 has but a single tooth thereon, while the gear 134 hasten teeth thereon. TheA construction of these gears 134 and 212 is such that the shaft 204 rotates through one-tenth of a rotation for every revolution of the shaft 174.

A preset travel indicator, in the form of a rotatable counter 214 similar to the counter 166, is also mounted in the housing 168 and the protective cover 170 is provided with `a second clear plastic window 216 (Figure 7) registering with the face of the counter 214. The stem of the Acounter 214 is connected to the other projecting end of the shaft 204 by a connection which permits relative axial movement between the stem and the shaft, as by a slot 220 inone end of the shaft 204 engaging atransverse pin 222 within a tubularmember or sleeve` 224 fastened to the stem 218 of the counter 214. The counter 214 is constructed to register the revolutions of the shaft 204 in terms of inches .and tenths of an inch of advance of the boring bar 74 through a preset feed distance. f

Intermediate its length, the shaft 204 is threaded and has an elongated, automatic feed nut 226 engaged therewith. Enclosing the nut `226 is an automatic feed tube 228 which is restrained against rotation but fixed to the shaft 204 ,for axial movement therewith, as by means of an inturned circumferential flange 230 on the tube interposed between the hub of the gear 208 and a thrust washer 232 bearing against a thrust collar 234 fixed on or integralwith the shaft 204. The tube 228 has a longitudinal slot 236 throughout a portion of its length for the reception 'of a radial lug 2,38 on the nut 226 to restrain rotation of the latter on rotation of the shaft 204. Consequently, rotation of the shaft 204 moves thek Y nut 226 axially therealong. Fixed on the automatic feed tube 228 is a radial arm 240 (Figures 5, 6, 12, and 19) which serves the dual functions of restraining the tube 228 against rotation and also arresting rotation of the cam sleeve 146 when the shaft 204 is shifted to the left to disengage the gears 208 and 132. For this purpose the yarm 240 has an aperture thereinrotatably receiving a portion of the cam sleeve 146. A counterbore 242 .at one end of the aperture is provided with a radial lug 244 (Figure 19) engageablewith a radial lug 246 on and adjacent one end ofthe cam sleeve 146, when the arm 240 is shifted to the left Vwiththe automatic feed tube 228, to arrest or prevent rotation of the cam sleeve.` As previously described, such arrestment will automatically shift the countershaft 122 from automatic to hand feed position.

The` automatic feed tube 228, `and consequently the l adjustable shaft 204, are constantly urged to shift to the left, into the axial position wherein the gears 208 and 132 are disengaged andthe lugs 244 and 246 are engaged, by a spring 248 surrounding the feed tube and interposed between the arm 240 andthe top cap 44 of the gear housing 46. In order to retain theshaft 204 in its righthand gear-engaging and lug-disengaging position against the action of the spring 248, there `is provided a detent or trigger mechanism in the form of a beveled shoulder 250 (Figure 5) on the tube 228 engaging a complementary shoulder 252 in an oversized aperture in the rocker arm 140 receiving the automatic feed tube. The rocker arm 140 is urged into a position to retain the beveled shoulders 250 and 252 in engagement against the `action of the spring248 by a plunger 254 (Figures 8 and 10) slidable in a bore in the rocker arm extending radially of the aperture and urged against a side of the automatic feed tube 228 by a spring 256. The friction thus developed between the interengaged shoulders 250 andl252 normally, is sufficient to retain the shaft 204 in its righthand position shown in Figure 5, but if sulicient axial shifting force is applied to the shaft 204, the resulting camming action of the interengaged shoulders 250 and 252 will rock the arm and release the shoulders and thus permit the spring 248 to shift the shaft 204 to the left to consequently disengage the gears 20S and 132 and shift the countershaft 122 from itshand feed to automatic feed position.

`In order to operate the aforedescribed preset feed mechanism. the knob 210 is pushed inwardly to rock the arm its; until the shoulders 250 and 252 are disengaged to permit the shaft 204 to shift to the left and disengage the gears 2% and 132. Thereupon the knob can be rotated to move the nut 226 axially along the shaft 204 and set the counter 214 for any desired distance of travel, up to a maximum of approximately l0 inches, which has been designed into the machine illustrated. When the shaft 284 is in its right-hand position and the automatic feed nut 226 abuts against the top cap 44, i. e., against the inner end of the bearing 206, the counter 214 is set to zero. lt thus will be seen that as the shaft 204 is rotated to set the preset feed mechanism, the automatic feed nut 226 travels to the left along the shaft until the right-hand end of the nut is a predetermined distance from the top cap 44 of the gear housing 46. At the same time, this distance is registered on the counter 214 in terms of inches and tenths of an inch of predetermined l travel of the boring bar 74. For example, when the nut 226 nearly abuts the collar 234, the counter may register 9.8 inches, as shown in Figure 5. Thereupon, the knob 21E) is pulled out to shift the shaft 204 to the right, against the action of the spring 248, to thereby engage the gears 203 and 132 and disengage the stop lugs 244 and 246. The shaft 204 is then held inthis position by the re-engagement of the detent shoulders 250 and 252.

When the machine is then operated in automatic feed, it will be seen that the shaft 204 will rotate in the opposite direction from its manual setting direction, so that the nut 226 will travel along to the right until it engages the top cap 44 of the gear housing 46, whereupon a reaction thrust will be exerted on the automatic feed tube 228 which causes disengagement of the aforementioned detent shoulders 250 and 252 and permits the spring 248 to move the shaft 2th! to the left, thus disengaging the gears 208 and 132 and causing the countershaft 122 to shift from automatic to hand feed position.

in connection with the foregoing preset feed mechanism, it will be seen that unless the pitch of the threads on the shaft 204 is impractically small, such threads would have to be of undue length unless the shaft has a reduction drive from the shaft 174. `The gears 212 and 134 provide such reduction. It also will be seen that as the shaft 204 is rotated by the reduction drive, the rotatable counter $.14 will return to a zero indication during travel Vof the boring bar 74 through its preset feed distance.

It also will be noted that the machine cannot be operated in automatic drive unless a preset feed distance is set into the preset feed mechanism.

The machine also embodies mechanism for positively preventing overtravel in the event that the boring bar 74 has advanced to nearly its maximum extended position and the automatic feed mechanism is inadvertently preset to advance the boring bar beyond such maximum extended position. Unless such overtravel preventing mechanism is provided, the downwardly facing shoulder 78 at the upper end of the boring bar 74 would engage the bottom wall of the lower gear housing 34 and thus possibly damage the machine considerably when it is power driven.

The overtravel preventing mechanism also involves the rocker arm 140 which is provided with another aperture having a bushing 258 eccentrically receiving the feed screw extension M2 when the arm 140- is in the position wherein the detent shoulders 250 and 252 are engaged. The edges of the bushing 258 are beveled for cammingengagement to center the bushing with respect to the extension 102 9 and thereby rock the arm 140, by a correspondingly beveled washer 260 carried by a pin 262 (Figure 3) extending through a diametric slot `264 in the feed screw extension 102.- A rod 266 is secured to the pin 262 and extends through the screw 100 to a point opposite diametric slots 268 (Figure 20) in and adjacent the lower end of the screw. At and beyond the slots 268, the feed screw 100 is reduced and provided with a smooth, unthreaded portion slidably mounting a collar 270 engageable by the ring 90, which is engaged with the feed nut 92, just before the shoulder on the bar '74, at its limit of advance, engages the lower wall of the housing 34. The collar 270 is fixed to the rod 266 by a transverse pin 272 extending through the slots 268 in the feed screw 100. A spring 274 interposed between the collar 270 and a second vcollar 276 fixed on the lower end ofthe feed screw 100 by a pin 278 urges the rod 266 into an upward position to relieve any camming action between the Washer 260 and the arm 140 or bushing 258. Engagement of the ring 9i) with the collar 270 pulls the beveled washer 260 into the bushing 258 to effect a camming action between their beveled surfaces that causes the arm 140 to rock in a direction tok disengage the detent shoulders 259 and 252 on the arm 140 and on the automatic feed tube 22S. Consequently, the latter will be shifted by the spring 248 to a hand feed position.

As pointed out heretofore, when a positively-engageable clutch mechanism is disengaged under load, the result is to damage such mechanism. Moreover, disengagement of such a mechanism under load usually requires an extremely large force. For example, it is estimated that when the machine illustrated is of a size to make a 6 inch diameter cut and is making such a cut in automatic feed, the load on the dive key 152 is 750 pounds, and that part of vthe key engaged with the gear 136 is under a pressure of 5,000 pounds per square inch when fully engaged. Such pressure increases substantially to infinity as the key 152 is cammed out of the groove 154. Consequently, if the dive key 152 is disengaged when theV power train constituting the automatic drive for the' feed mechanism is under load, not only would metal be shaved from the key and/or from the sidewalls of the groove 154 in the gear 136, but also it would require a considerable force to shift the countershaft 122 from its hand feed to automatic feed position. y

This invention overcomes the aforedescribed disadvantages by providing means to relieve the load on the power train on shifting of the countershaft 122 from its hand feed to its automatic feed position. This feature is particularly advantageous in the; instant machine wherein the preset feed mechanism automatically disengages the automatic drive for the feed mechanism when such drive is under load.

The load-relieving function is accomplished by securing the gear 144 to the countershaft 122 by a special key 280 engaging a special keyway 282 in the countershaft 122, shown best in Figures 14 to 17. The keyway 282 and that portion 2%4 of the key 280 engaged therein are formedv as sections of a helix Ahaving a direction and angle such that when the countershaft 122 is shifted from its hand feed (Figure 14) to its automatic feed position (Figure 15), the gear 144 is rotated relative to the countershaft in a direction to relieve the load on the power train comprising the automatic drive for the feed mechanism. In vother words, such axial shifting of the countershaft 122 effects a slightly backward rotation of the gear 144 relative to its normal direction of rotation when the automatic drive is operative. Thus, the load on the power train is relieved at the moment when `the dive key 152 disengages from the slot `or groove'154 in the gear 136 so that such clutch mechanism'will not be damaged. l

It will be seen that the load can -be thus relieved substantially at the commencement of axial shifting movement of the countershaft. Nevertheless, shifting motion of the countershaft 122 is essential torelieve the load, so

10 that at the commencement of such shifting motion, the load is not relieved and it still requires a considerable force to initiate such shifting motion. vThis disadvantage is overcome by forming the base or foot portion of the train is relieved before the commencement of disengaging motion of the clutch device. Consequently, only a small force is needed to automatically shift the countershaft 122 from hand feed to automatic feed position.

In some instances, a cut may be completed before the boring bar travels through the :distance set into the preset feed mechanism, so that the latter will not be operated to disengage the automatiic drive for the feed mechanism. In that event, an operator may shut off the driving motor, push in the knob 128 to place the machine in hand feed, and retract the bar by reverse rotation of the crank 114. Such reverserotation of the crank 114, with the shaft 204 still in its righthand position, because the detent shoulders 250 and 252 are still engaged, causes the nut 226 to travel along to the left. Should the nut 226 engage the collar 234 while the gears 208 and 132 are still engaged, continued reverse rotation of the crank 114 might seriously damage the preset feed mechanism.

rIhe aforementioned possibility of damage to the preset feed mechanism is avoided, however, by providing the lug 238 on the nut 226 with a beveled surface 251 Vopposed to the beveled shoulder 252, and so positioning the surface 251 on the nut that the surface 251 will engage the detent shoulder 252 immediately before the nut 226 could engage the collar 234. Such engagement of the surface 251 with the shoulder 252 cams the rocker arm to release the detent shoulders 25) and 252 so that the spring 248 will shift the shaft 204 to the left and disengage the gears 268 and 132. Consequently the boring bar can be fully retracted by the crank 114 without damage to the preset feed mechanism.

It thus will be seen that the objects of this invention have been fully and effectively accomplished. It will be realized, however, that the foregoing specific embodiment has been shown and described only for the purpose of illustrating the principles of this invention and is subject to extensive change without departure from such principles. Therefore, this invention includes all modilications encompassed within the spirit and scope of the following claims.

I claim:

l. In a machine having a translatable and rotatable part and a pair of interengaged, relatively rotatable elements, one rotatable with the part, for effecting translation of the part on relative rotation between the elements, the combination of:` differential gearing meanshaving two relatively rotatable members and a third member which rotates at the differential rate of rotation between said two members; means for driving one of said twomembers with one of the elements and for driving the other of said two members with the other of the elements; and rotatable counter means driven by said third member for measuring the extent of translation of the part.

2. In aV drilling machine having an axially and rotatably movable boring bar and feed mechanism to advance or retract vthe Abar including -interengaged feed nut and feed screw elements, one rotatable with the bar, the combination of: differential gearing means having two relatively rotatable members'and a third member which rotates at the dierential rate of rotation between said two members', means for driving one of said two members with one of the feed mechanism elements and for driving the other member with the other element; and rotatable counter l 1 means driven by said third member for measuring the extent of axial movement of the bar.

3. In a drilling machine having an axially and rotatably movable boring bar, feed mechanism therefor rincluding interengaged feed nut and feed screw elements, one rotatable with the bar, an automatic drive for the feed mechanism to advance the bar at a certain rate, shiftable means for rendering the automatic drive operative or inoperative,

and a manually-operable drive for the feed mechanism to advance or retract the bar at a different rate when the automatic drive is inoperative, the combination of: differential gearing means having two relatively rotatable members and a third member which rotates at the differential rate of rotation between said two members; means for driving one of said two members with one of the feed mechanism elements and for driving the other member with the other element; and rotatable counter means driven by said third member for measuring the extent of axial movement of the bar.

4. A drilling machine comprising: a support, a boring bar mounted therein for axial and rotary movement; a drive for rotating said bar; feed mechanism for said bar including a feed nut element and a feed screw element engaged therewith, one carried by said bar and the other by said support; means operable by the drive for the bar for automatically driving said feed elements relative to each other to move said bar axially at a rate proportional to its rate of rotation; clutch means in said automatic driving means; manually-operable means for driving one of said feed elements relative to the other to move said bar axially when said clutch means is disengaged; differential gearing means having two relatively rotatable members and a third member which rotates at the diifercntial rate of rotation between said members; means for driving one of said two members with one of said feed elements and for driving the other member with the other element; and rotatable counter means driven by said third member for constantly indicating the extent of axial displacement of said bar from a reference position.

5. in a machine having a translatable and rotatable part, feed mechanism therefor, and a disconnectable automatic drive for the feed mechanism operable on rctation of the part to effect translation thereof, the combination of settable mechanism operable with the drive and independent of translation resistance encountered by the part for automatically disconnecting the drive on a predetermined extent of translation of the part.

6. The structure defined in claim 5 including rotatable counter means operable by the settable mechanism for indicating the predetermined extent set by the settable mechanism.

7. The structure defined in claim 6 including means for driving the counter means with the automatic drive, after the settable mechanism is set, to return the counter means to a zero indication during translation of the part through the predetermined extent.

8. ln a drilling machine having an axially and rotatably movable boring bar, feed mechanism therefor, an automatic drive for the feed mechanism operable on rotation of the bar to effect advance thereof, and shiftable means for rendering the automatic drive operative or inoperative, the combination of settable mechanism operable with the drive and independent of feed resistance encountered by the bar for automatically shifting the shiftable means to render the automatic drive inoperative on a predetermined extent of advance ofthe bar.

9. A drilling machine comprising: a support; a boring bar mounted therein for axial and rotary movement; a drive for rotating said bar; feed mechanism operable by said drive for automatically .advancing said bar; clutch means in said mechanism; settable mechanism for disengaging said clutch means after a predetermined ad- Vance of said bar, including relatively rotatable, interengaged screw and nut elements; and-'disconnectablemeans for driving one of` said' elements relative to the other with said feed mechanism.

l0. The structure deined in claim 9 including rotatable counter means driven by the one element for indicating the predetermined advance set by the settable mechanism.

11. In a power train including a shaft member, a

gear member mounted thereon, and positively-engage-` able clutch means disengageable on relative axial movement between the members, the combination of means separate from the clutch means interconnecting the shaft and gear members for transmission of power from one to the other and responsive to the relative axial move- Vable clutch means disengageable on said relative axial movement; and key means interconnecting said members for transmission of power from oneto the other, said key means having a helical portion slidable in a complementary helical keyway in one of said members and esponsive to said relative axial movement to disengage said clutch means for effecting relative rotation between said members in a direction to relieve a load on the train.

14. In a power train the combination comprising: a shaft member; a pair of spaced gear members mounted thereon for relative axial movement between said gear members and shaft member; a dive key connected to said shaft member and engageable and disengageable with one of said gear members by'said relative axial movement; and key means interconnecting the other of said gear members and said shaft member for transmission of power from one to the other, said key means having a helical portion slidable in a complementary keyway in one of said members and responsive to said relative axial movement to disengage said dive key for effectingV relative rotation between said other gear and shaft members in a direction to relieve a load on the train. l

15. The structure defined in claim 14 including a lost motion connection between the dive key and the shaft member for delaying disengaging movement of the former until the load has been relieved.

16. In `a drilling machine having an axially and rotatably movable boring bar, feed mechanism therefor, an automatic drive for the feed mechanism operable on rotation of the bar to effect advance thereof and including a shaft member and a gear member mounted thereon for relative Aaxial movement therebetween and for transmissionof power from one to the other, and positively-engageable clutch means for rendering the drive operative or inoperative and engageable and disengageable by relative axial movement between the shaft and gear members, the combination of: ettable mechanism operable with the automatic drive for automatically effecting relative axial movement between the shaft and gear members in a direction to disengage the clutch means on a predetermined extent of advance of the bar; and helical key means interconnecting the shaft and gear mem s and effective on said disengaging relative axial movement to ycause relative rotary movement between the members in a direction to relieve a load on the automatic drive.

17. A drilling machine comprising: a support; a boring bar mounted therein for axial and rotary movement; a drive for rotating said bar-g feed mechanism operable by said drive for automatically advancing said bar; including a shaft member and a gear member mounted thereon for relative axial movement therebetween and for transmission of power from one to the other; positively-engageable clutch means in said feed mechanism and engageable and disengageable by said relative axial movement; settable mechanism for automatically effecting relative axial movement between said members to disengage said clutch means on a predetermined advance of said bar, including interengaged screw and nut elements and disconnectable means for driving one of said elements with said feed mechanism; and key means interconnecting said shaft and gear members for transmission of power from one to the other, said key means having a helical portion slidable in a complementary keyway in one of said members and effective on said clutch-disengaging relative axial movement to impart relative rotation between said members in a direction to relieve a load on said feed mechanism.

18. In a drilling machine having an laxially and rotatably movable boring bar, feed mechanism therefor including interengaged feed nut and feed screw elements, one rotatable with the bar, an automatic drive for the feed mechanism to advance the bar `at a certain rate, shiftable means for rendering the automatic drive operative or inoperative, and a manually-operable drive for the feedmechanism to advance or retract the bar at a different rate when the automatic drive is inoperative, the combination of: differential gearing means having two relatively rotatable members and a third member which rotates at the differential rate of rotation between said two members; means for driving one of said two members with one of the feed mechanism elements and for driving the other member with the other element; first rotatable Vcounter means driven by said third member for constantly indicating the extent of advance of the bar from a completely retracted position; settable mechanism operable by said third member for automatically shifting the shiftable means to render the automatic drive inoperative on a predetermined extent of advance of the bar from any given position; and second rotatable counter means operable with said settable mechanism for indicating the predetermined extent of advance set by said settable mechanism.

19. The structure defined in claim 18 including a driving connection between the settable mechanism and the second counter means for returning the latter to a zero indication during the predetermined extent of advance of the bar.

20. The structure defined in claim 18 including abutment means moving axially with the bar and means connected to the settable mechanism and engageable by said abutment means for operating the shiftable means to render the automatic drive inoperative at the limit of advance of the bar.

21. In a drilling machine having an axially and rotatably movable boring bar, feed mechanism therefor, an automatic drive for the feed mechanism including an axially-shiftable shaft offset from the bar, and clutch mechanism in the automatic drive and operable by shifting the shaft, the combination comprising: a shaft-shifting assembly including a part rotatable with the shaft and effective on arresting of rotation of said part to shift the shaft and disengage the clutch mechanism; and settable mechanism for automatically effecting said arrestment on a predetermined extent of advance of the bar from any given position including an axially-shiftable assembly comprising interengaged screw and nut elements, one xed against rotation, disconnectable means for rotating the other of said elements with the automatic drive to effect axial movement of said one element, said means being disconnectable by shifting said assembly, manually operable means for rotating said other element to adjust the axial position of said one element on disconnection of said disconnectable means, detent means restraining shifting of said assembly in a direction to disconnect said disconnectable means, spring means urging said elements to shift in said direction, xed abutment means engageable by said one element to shift said assembly in said direction and means shiftable with said assembly for arresting rotation of said part.

22. The structure defined in claim 21 including a rotatable counter driven with the other element for indicating the predetermined extent of advance set in the mechanism.

23. The structure defined in claim 21 in which the feed mechanism includes interengaged feed nut and feed screw members, one rotatable with the bar and including differential gearing means having two relatively rotatable parts and a third part which rotates at the dierential rate of rotation between said two parts, means for driving one of said two parts with one of the members and the other part with the other member, another rotatable counter driven by said third part for constantly indicating the extent of axial displacement of the bar from a retracted position, and means for driving the disconnectable means by said third part.

24. The structure defined in claim 21 including abutment means movable with the bar and means engageable by said abutment means fat the limit of advance of the bar for releasing the detent means.

25. The structure dened in claim 24 in which the detent means includes a spring-biased rockable member and interengaged beveled shoulders on said rockable member and the other element, and the detent releasing means includes cam means for rocking said rockable member to disengage said shoulders.

26. In a machine having a translatable and rotatable element and a non-translatable element engaged therewith and rotatable relative thereto for effecting translation thereof, the combination of indicator means for showing the extent of translation of the translatable element comprising: differential means having two relatively rotatable members and a third member which moves at a rate proportional to the differential rate of rotation between said two members; means for driving one of said two members with one of the elements and for driving the other of said two members with the other of the elements; and indicia means associated with said third member for measuring the extent of translation of the translatable element.

References Cited in the file of this patent UNITED STATES PATENTS

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