US2680257A

US2680257A - Hand tapping machine

Info

Publication number: US2680257A
Application number: US187290A
Authority: US
Inventors: John C Haugeland
Original assignee: Individual
Current assignee: Individual
Priority date: 1950-09-28
Filing date: 1950-09-28
Publication date: 1954-06-08
Anticipated expiration: 1971-06-08

Description

June 1954 J. c. HAUGELAND HAND TAPRING MACHINE 2 Sheets-Sheet 1 Filed Sept. 28, 1950 B m m a 9 s b 7. W 1 nmv/iy/v m d wu I. 8 3 2 a 1 8 38 [Mr John (.Haugeland 3? J June 8, 1954 J. c. HAUGELAND 2,680,257

HAND TAPPING MACHINE 2 Sheets-Sheet 2 Filed Sept. 28, 1950- aim C'Jfaqgeland w Patented June 8, 1954 UNITED STATES PATENT OFFICE HAND TAPPING MACHINE John C. Haugeland, Rockford, Ill; Application September 28, 1950, Serial No. 187,290

11 Claims. 1

This invention relates to a new and improved hand tapping machine, designed more particularly for use on a conventional drill press, although the same is also adapted to be used as a hand tapping attachment on a lathe, arbor press, vertical mill, and other machine tools.

The principal object of my invention is to provide a precision hand tapper that is simple in construction and easy to operate and will speed up tapping and greatly reduce if not eliminate tap breakage, even when used by more or less unskilled men, and thus fill a great need in tool and die shops, machine shops, and elsewhere.

A salient feature of my improved device is the novel arrangement of compression springs inside the handwheel hub on opposite sides of a floating bushing between the hub and the thrust spindle that is mounted in the chuck, the floating bushing having a slip fit on the spindle and inside the hub, and, by virtue of its far spacing relative to the fixed bushing at the top of the handwheel hub, providing much closer accuracy of alignment, which is so important in a device of this kind. The springs thereby serve the double purpose of positioning the floating bushing and spring loading the tap for the tapping operation.

Another important feature of my improved device is the spring pressure pad slidable in the handwheel bore above the rotary locking pin and having an embossed central portion projecting downwardly to ride on the diametrically opposite sides of either of the flats provided on the pin so as to hold the pin releasably against turning accidentally from a locked position locking the tap holding adapter in the hub, the marginal portion of the pad resting on top of the tap holding adapter so as to transmit pressure to the adapter instead of the locking pin when and if the end of the spindle comes into contact with the pad in the setup operation preliminary to the performance of a tapping operation, the locking pin being of cylindrical form except for the milled off flats provided on the diametrically opposite sides of its intermediate portion so as to permit entry thereof edgewise through the narrow end of a keyhole slot provided therefor in the end of the tap holding adapter, after which the pin is adapted to be turned 90 to lock the adapter in place. Still another important feature is the novel form of adapter chuck itself, and the novel locking means therefor.

The invention is illustrated in the accompanying drawings, in which- Fig. 1 illustrates the preferred design of my improved device and is a view partly in front elevation and partly in vertical section on the broken line l-l of Fig. 2;

Fig. 2 is a plan view;

Fig. 3 is a view partly in side elevation and partly in vertical section on the broken line 3-3 of Fig. 2;

Figs. 4, 5 and 6 are two side views and an end view, respectively, of the tap holding adapter chuck, and

Fig. '7 i a view similar to Fig. 1 showing a modified or alternative construction.

Similar reference numerals are applied to corresponding parts in these seven views.

Referring first to Figs. 1 to 3, the reference numeral 8 designates the hardened steel spindle which is accurately ground to cylindrical form and provides a projecting shank portion 9 for entry and fastening in the usual way in the chuck I!) of a drill press, for example, the rest of the spindle serving as a pilot or guide H for entry freely in the bore l2 of a sleeve [3, forming the hub of a handwheel l3a. The latter is preferably of cast aluminum alloy for lightness and easier operation, and the bore I2 is, of course, accurately machined, inasmuch as the accuracy of alignment of the tap holding adapter chuck or tool holder M with respect to the spindle 8 depends to a large extent upon the accuracy with which bushings l5 and I 6 fit in this bore, as well as upon the spindle 8. Bushings I 5 and it are preferably of cast'bronze and, of course, are also accurately machined to a precision fit, bushing I5 having a press fit in bore l2 and a close working fit on spindle'fl, whereas bushing I6 has a close working fit externally in bore l2 and internally on spindle 8. A groove [1 is provided in spindle 8 to receive a split snap ring I8, which serves as an abutment for a washer I9, neither of which is large enough in diameter to contact the bore I2. Washer l9 serves as an abutment for the upper one of two coiled compression springs 20 and 2! received loosely in the bore l2 on opposite sides of the floating bushing IS. The springs 20 and 2| are of oil tempered spring wire and have their ends cut off squarely and ground smooth for smooth sliding action on the parts abutting the same. A spring pressure pad 22 in the form of a hardened steel washer or plate has a free fit peripherally in bore [2 and serves as the abutment for the lower end of the lower spring 2|. A locking pin 23 of hardened steel is of cylindrical form at both ends so as to fit rotatably in bearing holes 24 provided therefor in hub l3 on diametrically opposite sides of bore l2, an acorn nut 25 being threaded on one end;

which is suitably reduced and threaded for this. purpose, as indicated at 21, and an operating handle 28 being suitably aflixed to the other end. The lower portion of hub I3 is of square section, as indicated in Fig. 2, and flats 23 are machined on diametrically opposite sides of the hub l3 for smooth working abutment by the nut 25 and handle 28. Parallel flats are machined on diametrically opposite sides of the intermediate portion of pin 23, equivalent in length to the diameter of bore [2, for interlocking engagement in a keyhole slot 3| provided diametrically of the end of each of a series of tap holding adapters l4, each tap 32 of a set having its own adapter attached, so that dilferent sized taps can be used without the loss of time and inconvenience that would otherwise be involved in removing and inserting different taps used in one adapter.

The adapters or tool holders l 4 are cylindrical, as illustrated in Fig. 6, and of hardened steel, accurately ground to fit closely in the lower end of bore [2. An axial hole 33 is provided in the lower end of each adapter below a square axial bore 34 in which the square end of the shank of the tap is adapted to be entered, as shown in Figs. 1 and 3. A transverse hole 35 in the lower end of the adapter receives a set screw 36 for fastening the tap in place in the adapter.

In operation, the mechanic, having drilled the proper sized hole 31 in the piece of work 38, does as follows to tap the hole: Spindle 8 is first entered and secured in the chuck In of the drill press, or other machine tool. Then, the proper sized tap 32 is selected and its adapter or tool holder I4 is entered in the lower end of bore 12 of hub i3 and locked in place by pin 23, the flattened portion of the pin being entered edgewise in the narrow end of the keyhole slot 3| and the pin being then turned 90 to lock the adapter or tool holder securely in place. The downwardly projecting embossed central portion 40 of pad 22, which is raised slightly against pressure of springs 20 and 2| by the round portion of pin 23 when the pin is turned to move the flat portion to a vertical position for entry edgewise in slot 3| rides back under spring pressure onto the flat portion when the pin 23 is turned 90 to locking position, thereby serving to hold the locking pin releasably in locked position, so that there is no danger of the adapter l4 being accidentally released. The downward projection of the handle 28 is the position the handle would gravitate to and this, of course, also helps to insure the pin 23 staying in locked position. The pad also serves to protect the locking pin from damage in the event a mechanic lowers the drill press spindle too far; in that event the end of the spindle strikes the pad which, in turn, transfers the thrust to the adapter. It is in this operation that it is important that the spindle be large in diameter in relation to the width of the narrow upper end of the keyhole slot in the adapter, so that the pad or plate 22 is not distorted by the spindle pressure while such pressure is brought to bear on the looking pin 23. Instead, all spindle pressure is on the adapter. When the tap is locked properly, the drill press spindle can be lowered until the tap just touches the work. Then the reading (in inches) on the drill press depth scale should be taken. Next, the tap 32 is aligned with the hole 31 to be tapped, and the drill press spindle is lowered to the former reading plus the nominal diameter of the tap. That is, if the scale reads 2" in the previous step, the spindle should be lowered so the scale reads 2%" if the tap is a A tap, or 2 for a tap, etc. Then the drill press spindle is locked. The lowering of the spindle causes hub i3 and bushing 15 to ride upwardly on the spindle 8; this compresses the

springs

23 and 21 enough to give the tap the right amount of axial thrust required to start cutting a thread, the springs being calculated to give such results for any size of hole in a selected material, like, for, example, mild steel. By this method of gauging the axial force exerted by the springs 292l on the tap necessary to make it start cutting a thread, good results are insured and breakage of taps avoided. Under no circumstances will the mechanic ever lean on the handwheel to start the tap in the hole. Now, the wheel Him is turned a few revolutions to engage the tap, and then the drill press spindle lock is released. The drill press spindle will be forced up by its own return spring and by the springs ZB-Zl in the tapper. The reading on the drill press depth scale minus the original reading taken will show the exact depth to which the tap has penetrated the work. It should be noted that the drill press spindle, belt, motor, etc., do not turn when the handwheel !3a is turned. Consequently, the mechanic has a better feel in the progress of the tap in tapping and it requires less real work to do the tapping. The tapping is continued by further turning of the handwheel 13a until the tap has penetrated the desired distance (blind tapping) as indicated on the drill press depth scale. Finally, the tap is released from the work by turning the handwheel [3a in the reverse direction, after which the spindle 8 is removed from the chuck Ill, unless, of course, another or other holes are to be tapped. If another sized tap is required for a second hole, the first adapter is removed and the adapter having the desired tap in it is substituted. Close accuracy of alignment of the tap with the spindle is assured by providing the floating bushing 58 between the two springs 23 and 2|, because this bushing is, therefore, spaced to a maximum extent relative to bushing l5. Due to its floating in the bore l2, the bushing l6 does not interfere with the functioning of the springs, the latter shifting the bushing downwardly in hub l3 to a small extent to maintain a mid-position between washer I9 and pad 22 when the springs are compressed by the lowering of the drill press spindle, as above described, thereby giving the maximum spacing of bushing is relative to bushing I5 for maximum accuracy of guiding function under all operating conditions.

In the modified form shown in Fig. 7 the same general construction is used but there is only one coiled compression spring 20' between a bushing I6 and the pad 22, the bushing it having a press fit on spindle 8 and a close working fit in bore I2.

The mode of operation of this device is the same, but, due to the closer spacing of bushings l5 and 16, the accuracy of alignment is not as close.

It is believed the foregoing description conveys a good understanding of the objects and advantages of my invention. The appended claims have been drawn to cover all legitimate modifications and adaptations.

I claim:

1. A device of the character described compris ing a spindle, one end portion of which is adapted to be gripped in a chuck, a sleeve surrounding the major portion of the rest of the length of said spindle, whereby the latter is adapted to serve as a guide therefor, manually operable handle means on the sleeve for turning the same, said sleeve having an accurately formed bore provided therein larger in diameter than said spindle, whereby to provide space for spring means between said parts, means on the sleeve defining a reduction in diameter of the bore at the upper end to form a guide bearing slidable on the spindle, coiled compression spring means surrounding said spindle inside said sleeve and disposed in downwardly spaced relation to said guide bearing, the lower end of the bore being adapted to mount therein a tool holder carrying a tap in coaxial relation to said spindle, means on the sleeve adapted for looking a tool holder in the sleeve against turning and against displacement relative to the sleeve, said means being formed to provide a retaining abutment for the lower end of said spring means when the tool holder is removed, and means surrounding the spindle providing another abutment for said spring means and a guide bearing for the sleeve on the spindle in downwardly spaced relation to the first mentioned guide hearing but above the tool holder locking means, whereby when the spindle is moved downwardly relative to said sleeve said spring means is compressed to exert end thrust on the tool holder in proportion to the compression.

2. A device as set forth in claim 1, wherein the means surrounding the spindle providing another abutment for said spring means and a guide bearing for the sleeve on the spindle comprises a bushing fixed internally to the spindle and having a close working fit externally in the bore in said sleeve.

3. A device as set forth in claim 1, wherein the coiled compression spring means comprises two coiled springs surrounding the spindle, the device including a spring abutment fixed on the spindle engaging the upper end of the upper one of said springs to prevent upward displacement thereof, the means surrounding the spindle providing another abutment for said spring means and a guide bearing for the sleeve on the spindle comprising a bushing slidable closely on the spindle and disposed between and abutting the adjacent ends of the two springs and having a close sliding fit inside the sleeve and on the spindle.

i. A device of the character described comprising a spindle, one end portion of which is adapted to be gripped in a chuck, a sleeve surrounding the major portion of the rest of the length of said spindle, whereby the latter is adapted to serve as a guide therefor, manually operable handle means on the sleeve for turning the same, said sleeve having an accurately formed bore provided therein larger in diameter than said spindle, whereby to provide space for spring means between said parts, means on the sleeve defining a reduction in diameter of the bore at the upper end to form a guide bearing slidablc on the spindle, coiled compression spring means surrounding said spindle inside said sleeve and disposed in downwardly spaced relation to said guide bearing, means surrounding the spindle in downwardly spaced relation to said guide bearing providing one abutment for said spring means and a guide bearing for the sleeve on the spindle, and a locking pin extending diametrically of the lower end portion of said sleeve adapted to serve as another abutment for said spring means and prevent displacement thereof from the sleeve, the lower end of the bore being adapted to mount therein a tool holder carrying a tap in coaxial relation to said spindle, said locking pin being adapted for detachable connection with the end of the tool hold-'- er to secure it against turning and against displacement relative to the sleeve, the assembly as described caging said spring means so that when the spindle is moved downwardly relative to said sleeve said spring means is compressed to exert end thrust on the tool holder in proportion to the compression.

5. A device of the character described comprising a spindle, one end portion of which is adapted to be gripped in a chuck, a sleeve surrounding the major portion of the rest of the length of said spindle, whereby the latter is adapted to serve as a guide therefor, manually operable handle means on the sleeve for turning the same, said sleeve having an accurately formed bore provided therein larger in diameter than said spindle, whereby to provide space for spring means between said parts, means on the sleeve defining a reduction in diameter of the bore at the upper end to form a guide bearing slidable on the spindle, coiled compression spring means surrounding said spindle inside said sleeve and disposed in downwardly spaced relation to said guide bearing, means surrounding the spindle in downwardly spaced relation to said guide bearing providing one abutment for said spring means and a guide bearing for the sleeve on the spindle, a circular plate slidable up and down in the lower end of the bore providing another abutment for said spring means, a rotary cylindrical locking pin extending diametrically of the lower portion of said sleeve immediately under said plate and rotatably received in bearing holes provided therefor in the sleeve thus preventing displacement of the plate and spring means from the sleeve, said pin having portions on its diametrically opposite sides cut away to define flats on opposite sides of a reduced portion that is adapted to be received in the end of a tool holder to secure it against turning and against displacement relative to the sleeve, the lower end of the bore being adapted to mount therein a tool holder carrying a tap in coaxial relation to said spindle, said plate having a downwardly projecting central portion arranged to engage either of the flats on the pin under spring pressure and hold it releasably in locked position, the assembly as described caging said spring means so that when the spindle is moved downwardly relative to said sleeve said spring means is compressed to exert end thrust on the tool holder in proportion to the compression.

6. A device as set forth in claim 5, wherein means for turning the pin comprises a handle fixed to and extending radially relative to one end of said pin and arranged so as to be in a pendant relation to the end of said pin when the pin is in locking position, whereby gravity assists in holding the pin releasably in locked position.

7. In combination, a tool holder sleeve having a cylindrical bore, an adapter chuck for mounting a tool, such as a tap, comprising a cylindrical body adapted to be entered with a close fit in the open end of said bore and having an axial bore in the lower end adapted to receive the shank of the tool, said cylindrical body having provided in its upper end a keyhole shaped slot diametrically thereof with the small end open to the top of said body, a cylindrical locking pin extending diametrically of the lower portion of said sleeve and rotatably received in bearing holes provided therefor in the sleeve, said pin having portions on its opposite sides cut away to define a reduced portion which is thin enough to permit entry thereof edgewise through the small end of said keyhole slot, the wider portion of said slotbeing of approximately the same diameter as said pin, means for turn ng said pin to and from locking position in the wider portion of said slot, and a coiled compression spring housed in the sleeve in compressed condition and bearing at its lower end on a plate that is slidable in the sleeve normal to the axis thereof and arranged to rest on the pin when the adapter chuck is removed, said plate having a downwardly projecting central portion engageable with either of the flats on the pin under spring pressure through the narrow portion of the keyhole slot to hold the pin releasably in looking position.

8. The combination set forth in claim 7, including a guide spindle coaxially arranged with respect to the sleeve and slida bly engaged in the upper end of the bore and disposed in telescoping relation to the coiled compression spring, the diameter of said spindle being greater than the width of the narrow portion of the keyhole slot, so that if the spindle is moved downwardly into abutment with the plate, during "a tapping operation, for example, the thrust is transmitted to the adapter without deflection of the plate and substantially independently of the locking pin.

9. In combination, a tool holder sleeve having a cylindrical bore, an adapt-er chuck for mounting a tool, such as a tap, comprising a cylindrical body adapted to be entered with a close fit in the open end of said bore and having an axial bore in the lower end adapted to receive the shank of the tool, said cylinder body having provided in its upper end a keyhole-shaped slot diametrically thereof with the small end open to the top of said body, a cylindrical locking pin extending diametrically of the lower portion of said sleeve and rotatably received in bearing holes provided therefor in the sleeve, said pin having portions on its opposite sides cut away to define a reduced portion which is thin enough to permit entry thereof edgewise through the small end of said keyhole slot, the wider portion of said slot being of approximately the same diameter as said pin, means for turning said pin to and from looking position in the wider portion of said slot, a coiled compression spring housed in the sleeve in compressed condition above the locking pin to exert pressure endwise on the adapter chuck, and a guide spindle coaxia-lly arranged with respect to the sleeve and slidably engaged in the upper end of the bore and disposed in telescoping relation to the coiled compression spring, the diameter of said spindle being greater than the width of the narrow portion of the keyhole slot, so that if the spindle is moved downwardly to an extreme position relative to the sleeve, during a tapping operation, for example, it exerts pressure on the adapter chuck substantially independent of the locking pin.

10. A device of the character described, comprising a guide spindle adapted to be mounted in a chuck and advanced toward a work piece, a tool holder normally in spaced coaxial alignment with the spindle, a sleeve slidable on the spindle as a guide and having the tool holder fixed in its one end, said sleeve providing a chamber therein around the spindle, two coiled compression springs with a bushing therebetween disposed in said chamber, the springs encircling the spindle and the bushing having a close sliding fit on the spindle and inside the sleeve, there being a shoulder on the spindle engaging the upper end of the upper spring, the lower end of the lower spring being arranged to exert pressure on the tool holder, so that the spring pressure on the tool in the tool holder varies according to the proximity of the spindle to the tool holder, and manually operable handle means on the sleeve for turning the same.

11. A device of the character described, comprising a guide spindle adapted to be mounted in a chuck and advanced toward a work piece, a tool holder normally in spaced coaxial alignment with the spindle, a rotary sleeve slidable on the spindle as a guide and having the tool holder fixed in its one end, said sleeve providing a chamber therein around the spindle, and two coiled compression springs with a bushing therebetween disposed in said chamber, the springs encircling the spindle and the bushing having a close sliding fit on the spindle and inside the sleeve, there being a shoulder on the spindle engaging the upper end of the upper spring, the lower end of the lower spring being arranged to exert pressure on the tool holder, so that the spring pressure on the tool in the tool holder varies according to the proximity of the spindle to the tool holder.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 803,840 Miller Nov. 7, 1905 880,529 Heynau Mar. 3, 1908 1,453,204 Stokes Apr. 24, 1923 1,936,665 Gauthier Nov. 28, 1933 1,958,817 Gase May 15, 1934 2,399,966 Welch May 7, 1946 2,465,541 Kreshock Mar. 29, 1949 OTHER REFERENCES Burton, March 1948, Popular Mechanics.