US2277213A - Thread grinding machine - Google Patents

Description

March 24, 1942. w, DALZEN 1 2,277,213

THREAD GRINDING MACHINE Filed April 19, 1941 6 Sheets-Sheet 1 INVENTOR.

prr mvry March 24, 1942. w. F. DALZEN 2,277,213

THREAD GRINDING MACHINE Filed April 19, 1941 6 Sheets-Sheet 2 INVENTOR, BY Wm March 24, 1942. w. F. DALZEN 2,277,213

THREAD GRINDING MACHINE Filed April 19, 1941 6 Sheets-Sheet 3 INVENTOR.

HTTOENE) March"24, 1942. w. F. DALZEN 2,277,213

THREAD GRINDING MACHINE Filed April 19, 1941 6 Sheets-Sheet 4 March 24, 1942.

w. F. DALZEN 2,277,213

THREAD GRINDING MACHINE Filed April 19,- 1941 e sheetg-sheet s Filed April 19, 1941 6 Sheets-Sheet 6 ?aienied Mar. 24, 1%42 I ES 27 Claims.

This invention relates to cutting and grinding machines and more particularly to thread grinding machines.

Hertofore devices of this type have been com plicated by unnecessary machinery and working parts whereby said machines have been diilicult and expensive to manufacture.

Due to the largeness and complicated nature of machines of this type the cost of maintenance has been higher and the accuracy thereof has been reduced due to wear on more workingparts. It is therefore the object of this invention to provide a thread grinding machine which dueto its simplicity is far more accurate than machines of this type heretofore constructed.

It is the object of this invention to provide a thread grinding machine of simple construction having a minimum number of parts, built at considerably less expense than heretofore expended for machines of this type.

It is the further object hereof to provide a thread grinding machine with a maximum production capacity in excess of similar machines of this type.

It is the further object of this invention to provide in a thread grinding machine and in combination therewith a novel grinding wheel form dresser adapted to produce various shaped surfaces in the edge of the abrasive grinding wheel for accurately grinding out various shapes of threads. Y

It is the further object hereof to provide in said dressing mechanism an auxiliary dressing attachment for producing a curved surface upon the outer peripheral edge of the abrasive grinding wheel.

It is the still further object herein to provide a simple cam attachment for said machine whereby radial relief may be obtained in making taps, reamers, or similar tools, or other articles be reproduced in the work if desired.

It is the still further object hereof to provide means for supporting-a rotatable grinding wheel above the work, together with means for raising where it is desired to vary the radial diameter at certain circumferentially spaced points upon a cut or ground surface.

It is the still further object of this invention to provide a novel run out slide whereby at the end of the threads and on the last thread, the work is gradually dropped away from the cutting wheel, giving a gradual run out from the root diameter of the thread to the extreme outside diameter of the part.

It is the still further object of this invention to provide a carriage supporting slide mechanism which may be angularly adjusted with respect to the horizontal for producing a taper in the work supported by said carriage. On the other hand,

and lowering said wheel with respect thereto.

It is the still further object herein to provide a vertically adjustable tail stock for supporting a rotatable work whereby a taper in either direction may be cut or ground thereon.

It is the still further object hereof to provide compensating means for raising and lowering the grinding wheel support and also the dresser with a proportional movement of the latter with re spect to said support.

Other objects will be seen in the various arrangements of parts and combinations thereof as will be hereinafter described in connection with the appended drawings of which:

Figure 1 is a side elevational view of the thread grinding machine.

Figure 2 is a front elevational view of the same.

Figure 3 is a top plan view thereof.

Figure 4 is a side elevational view on the end opposite to that of Figure 1. I

Figure 5 is a fragmentary plan view showing the transmission and reversing mechanism.

Figure 6 is a fragmentary elevational view of the carriage, and support therefor.

Figure 7 is a fragmentary elevational view of the rocker, cam, carriage, and reversing mechanism.

The above drawings illustrate merely preferable embodiments of the invention, it being expressly understood that it is not intended that the invention be limited thereby.

In the drawings, a grinding wheel dresser is generally indicated as A with its housing H vertically and reciprocably mounted within the support l2 with friction minimizing ball races or ways 43 interposed therebetween. Support lZ is joined to the vertically movable grinding wheel support or housing I4 and is adapted to move therewith.

Hand wheel i5 operating through gears l6 and I1 turns the threaded shaft or screw l8 which. supported bycolumn l9, raises and lowers housing I and the abrasive grinding wheel 20 with respect to said column. The wheel dresser A and housing H are also raised and lowered by hand wheel l5 operating through the movable wheel support. It will be noted that wheel 20 may be a metal cutter where it would be desirable for cutting softer metals than that of which the cutter consists.

Lever 2| has a lug on its end adapted to support the housing I! of the dressing mechanism A. Said housing while resting upon the end of lever 2| is longitudinally and reciprocably journaled within the vertical support l2.

Said lever 2| is centrally pivoted at point 23 to the movable housing H which provides a movable the column l9. A washer is secured upon the endof screw 2| by a nut 23'; and'the end of lever 2| is beneath said washer. whereby a retaining means is provided preventing rotation of lever 2|.

A calibrated bolt H is threadably disposed on the lower end of the compensating screw 2| and thereby provides a manually operable adjusting means permitting longitudinal adjustment of the compensating screw 2| whereby the lever 2| is correspondingly adjusted as desired.

Housing |4 slides relatively to column IS with the dovetail 24, and as has been described, is adjustable with respect thereto bythehandwheel l5.

The wheel dressing mechanism is claimed in my divisional application Serial No. 423,517, filed December 18, 1941.

As seen in Figure 3 column 19 is angularly' adjustable upon the upper bed upon the arcuate T slots 26, with securing bolts 21 positioned through the lower portion of column 9 with the heads thereof slidably disposed within said T slots. By virtue of this arrangement the grinding wheel 28 may be angularly disposed to the desired angle of lead with respect to the work supported therebeneath in the manner hereinafter described.

In applicant's preferable embodiment, said 001- umn is adapted for arcuate adjustment through an arc of 45 degrees, which may be distributed proportionately on either side of center.

Bed 25 also longitudinally adjustable upon the base 28 is slidable with respect thereto by means of the T slots 29 therein. A threaded square headed shaft 30 is preferably employed for manually moving, by a suitable means, bed 25 with respect to said base member.

A basin or edging 3| is horizontally disposed upon the base member 28 for retaining the cooling oil after it has flowed from the work, whence it is conducted back to the fluid sump 32 within the base member 28.

A centrifugal pump 33 supported by said base member is in communication with the coolant sump 32, and is adapted to supply coolant through a suitable conduit to the point of engagement of the grinding wheel and work. From this point cooling fluid such as oil or other suitable composition descends to the basin 3| whence it returns to the sump 32.

As shown in Figure l, a removable shield or splash guard 34 is provided removably secured 2,277,213 to the front portion 'of basin 3| by clips 35 for protecting the operator from splashing oil.

A motor 36 is supported within column l9 and is joined to the grinding wheel spindle 31 by any suitable belting 38 or other connecting means with suitable means such as step pulleys employed for varying the speed of said spindle.

Another 'motor 39 is supported within base member 28 with a plurality of step pulleys 40 joined thereto for operable engagement selectively through belt 4| with a plurality of step pulleys 42 upon an idler 43 which in turn is joined by suitable pulleys 44 and 44' and a belt 45 for rotating sleeve 46 within a suitable bearing support 41. By' virtue of said pulleys a plurality 'of speeds for said sleeve may be obtained when desired. However, it will be noted that other variable means may be employed for connecting motor 39 with rotatable sleeve 46. Sleeve 46 opcrates drive shaft 48 with a speed-up transmission 49 interposed therebetween, said shaft being disposed concentrically within said sleeve.

Referring to Figures 1 and 5 a gear 58 secured upon sleeve 46 and rotatable therewith has on its outside edge a clutch member 5|. Shaft 48 has a gear 52 thereon rotatable therewith but adapted for a reciprocable sliding movement thereon over splines 53 in said shaft. The outside surface of gear 52'a1so has a clutch member 54 adapted for cooperating engagement with clutch member 5| when gear 52 is moved to the left in the manner hereinafter described. So moved, it is seen that sleeve 46 and drive shaft 48 move together with no speed up.

A speed-up gear 55 on shaft 56 is in mesh with gear 50 for operating gear 51, on the other end of said shaft. With gear 52 moved to the right it is in engagement with gear 51 whereby a speedup is obtained between sleeve 46 and drive shaft 48.

The means employed for longitudinally sliding gear 52 upon drive shaft 48 consists of a bifurcated stirrup or forked member 58 adapted to loosely engage the edges of gear 52 for sliding the same upon shaft 48 for engagement and disengagement of clutch members 5| and 54.

Forked member 58 is secured on the end of a manually actuated shaft 59 providing operative control for the above described transmission. In one position of gear 52 as at the left the connection between sleeve 46 and shaft 48 is direct. With gear 52 moved to the right by shaft 59 sleeve 46 is indirectly joined to shaft 48 throughthe speed-up transmission gears 50, 55, 51 and 52.

' Gear 68 on the end of drive shaft 48 is in engagement with gear 6|, with the latter loosely journaled upon shaft 62 and rotatable independently thereof. A reverse gear 63 in spaced Y relation to gear 6| is also loosely journaled around shaft 62 and movable independently thereof, but meshing with gear 69.

A clutch member 64 is slidably disposed upon shaft 62, movable therewith but adapted to positions of engagement with either gear 6| or gear 63 or in aneutral position therebetween.

Said clutch64 is therefore adapted to turn with either gear 6| or 63 whereby shaft 62 is turned in one direction or the reverse thereof.

The position of clutch 64 upon shaft 62 is regulated by a manually actuated latch or handle 65 disposed in the front of the thread grinding machine and adapted for movement to the left and to the right.

A-shaft 66 is joined to said handle and has on its end a gear 61 which is in mesh with a similar gear 68' for turning another shaft 69. A gear I8 is on the end of shaft 69 and cooperatively engages clutch 84 by means of a rack gear II thereon. I

Consequently movement of handle 85 causes a corresponding movement of clutch 64 for disengaging drive shaft 82 from drive shaft 48, and for regulating the movement of said drive shaft 62 in one direction or the other. This manual control also regulates the reciprocable movement of the work supporting spindle and also the rotatory movement of the work with respect to the grinding wheel 20. Y

Referring-to Figures -9 and 7 it is seen that the manual control 85 has a roller member 86" adapted to be engaged by the vertically disposed stops 61' secured to the reciprocable work support carriage 68. It will be noted that these stops 61' are adapted to longitudinal adjustment and are secured to themovable carriage by suitable securing means 69'.

In operation, with said carriage moving in one direction, when one of said stops engages the roller 68' on the handle 65 said handle is turned to a neutral position which automatically disengages the drive shaft 62 by means of the clutch mechanism 84 hereinbefore described.

Shaft 62 has near its end a gear I2 in mesh with gear I3 for providing rotative motion of the lead screws I4 to which it is attached. The opposite end of said lead screw'is supported by a longitudinally adjustable tailstock I50 thereby permitting the use of different lengths of lead screws if required.

It will be noted that the lead screw is adapted to cause reciprocable movement of a work supporting carriage 68 with respect to the rotative grinding wheel 28, and is also adapted to cause rotation of the work itself in the manner hereinafter described.

A suitable nut I5, wedged up against the under side of the reciprocable-carriage 68 by means of a manually actuated eccentric pin I5',threadably engages said lead screw I4 causing reciprocable sliding movement of carriage 68 with the direction thereof governed by the direction of movement of said lead screw. It is seen that merely by turning the eccentric pin I5 that nut I5 carrying lead screw I4 is securely locked in place. More particularly a lug I50 downwardly depends at right angles from the carriage 88, and has a longitudinal slot I5 I therethrough. The nut I5 for the lead screw I4 is adapted to have its bottom portion snugly disposed within slot iii. A stop plate I52 is suitably secured, to lug I50 on one side of slot I5I adjacentoneedge of nut I5 limiting movement thereof with respect to lug I50 and carriage 68.

The eccentric pin I5 engages the opposite edge of nut I5 ,wedging the same, when operative, against the stop plate I52. Thus the nut I5, maintained securely against the underside of carriage 68 by lug I58 and eccentric pin I5 is adapted to reciprocably actuate said carriage upon rotation in one direction or the other of lead screw 14. It will be noted that suitable means are employed as hereinabove described whereby the direction of motion thereof is manually or automatically reversed or disengaged.

Reversal of the direction of movement of lead screw I4 in turn results in reversal of the longitudinal movement of the work supporting carriage 68 and at the same time reversal of the direction of rotative movement of the work.

Gear I3 is also in mesh with gear I4 for tumcenter 18'. It will be understood that said sleeve and center are removable to permit the Journaling of a long piece of work concentrically within the hollow spindle I8 if necessary. Other suitable work securing means may then be employed for retaining and supporting the work.

Longitudinal movement of the work supporting carriage 88 coincides with the rotary movement of the work supporting spindle It in one direction by means of the intermeshing gears I3 and .It may. be desirable, however, that for such movement of the carriage 68 that the work rotate in the opposite direction. To accomplish this a removable idler gear I3 supported by a suitable bracket 13" is in mesh with gear I3.

A manually actuated gear shifting fork I4" is adapted to engage the annularly recessed gear shifting means II which is secured to the spindle driving gear 14'. Movement of fork 14" causes gear I4 to move longitudinally upon spindle I6 on a suitable keyway or splines bringing said gear into mesh with the idler gear I3. So connected, the rotary motion of spindle I6 is thereby reversed independently of the work .carriage 68, and without changing the lead screw.

In this connection a tail stock I8 is also employed for supporting the work at its opposite end. Said tail stock adjustable horizontally upon a keyway I8 on the carriage, 68 for different lengths of work, is also adjustable vertically by suitable means, as for instance, a screw with a dovetail connection between said tall stock and support.v Thereby with vertical adjustment of said tail stock a taper in either direction may be put upon the work if desired.

Referring again to work carriage 68, as in Figures 1 and 7 it is seen that the same is angularly' supported with respect to the sub-table 8|. By interposing ball races or ways 82 along the entire engaging surfaces of said sub-table and work siipporting carriage, friction therebetween is minimized providing a free acting reciprocable movement for the latter.

Sub-table 8| pivotally secured to the lever atpoints 83 is angularly disposed and pivotally supported at its upper edge by hinge members 84 with the bearings 85 therefore loosely disposed around the shaft 62, and supported by the drive shaft bearings 86 which are in turn supported in the base 28 of the thread grinding machine. Thus it isseen that the sub-table 8I is pivotally supported about the axis of the drive shaft 62 as shown in Figures 8 and 10.

Gear 81 is joined to shaft 62 adapted to mesh with another gear 88 for operating a cam shaft 89. Cam 90 secured upon the end of said shaft is adapted to produce a reciprocable rocking movement of the sub-table 8|. This movement is employed wherever it is desired to obtain radial relief in the grinding of taps, reamers, or

similar tools. In other words, by this device the thread channel put on a tap or other tool may have a variable radius at certain circumferentially spaced points.

The cam- 90 is adapted to engage the upper surface of a lever 80 at one end thereof. A fulcrum 9| is provisioned beneath lever 80, and is supporting carriage 68 on which is disposed the.

work support 16, and also the tail stock I8.

Fulcrum Si is slidably adjustable with respect to a calibrated scale 92 under the lever whereby different degrees of movement are obtained for the sub-table 8|. It will be noted that the cam shaft 89 is adapted for disengagement with gear 88 whenever its use is not required.

A run-out slide mechanism is herein provided whereby at the end of the threads and on the last thread the work carriage 68 and sub-table 8i and the work are gradually dropped away from the cutting wheel, giving a gradual runout of the thread'channel from the root diameter of the thread to the extreme outside diameter of the work.

This eliminates the abrupt stoppage of the thread as has been the case heretofore. This point of stoppage has been a bending point between the threaded portion and the body portion, and as a result when breakage occurred, it oocurred in this point. By eliminating this abrupt stoppage of the thread and running the same out gradually to the extreme diameter of the part, bending is distributed over a greater length of the work.

The run-out slide mechanism as illustrated in Figure 2 consists of a longitudinally disposed supporting member 93 adjustably secured on the front of the base member 28 at points 94 with one end of said support angularly cut away as at 95. Guide means 96 depending downwardly from the reciprocable carriage 68 cooperatively register with the top surface of the supporting slide member 93 and support said carriage with respect thereto.

It will be noted that by adjustment of securing means such as screws at points 94, member 93 may be angularly disposed with respect to the horizontal. By so doing a gradual taper may be obtained throughout the length of the work if desired.

On the other hand member 93 may have an irregularly -shaped upper surface upon which guide 96 will register. shaped surfaces may be reproduced in the work supported by the movable carriage 68.

. It will be noted further in this connection that when grinding taps or reamers employing the use of the cam attachment 9!], heretofore described, that the run-out slide mechanism is disengaged.

- On the other hand when using the run-out slide 93 and support 96 the cam attachment 90' is disconnected.

As the work and table are moved to the right with the wheel 20 in grinding engagement with the rotated work, the guide 96 follows'the top surface of the slide 93. When said guide reaches the inclined portion 95 it is seen that the work support 68 is gradually dropped away from the grinding wheel 29 which results in a gradual run-out of the threads cut from the root diameter to the outside diameter of the work.

In grinding out threads upon a rotated work piece it will be seen that the .size and number of Consequently irregularly threads per inch varies with each job. Consequently the correct pitch is obtained by making the lead screw 14 and nut 15 readily removable and interchangeable with others of different pitches. Therefore it is seen that the thread grinding device described herein has a multiplicity of uses and its versatility and adaptability to various types of jobs is apparent;

It will be noted from the above description that the thread grinding mechanism provides driving means for reciprocating the work supporting carriage 69 in the form of a lead screw M and also atthe same time provides intermeshing means 13 and M for rotating the work throughout reciprocable movement thereof.

From time to time the grinding wheel 20 becomes worn requiring a dressing operation; or on the other hand it may be desired to vary the form of the cutting edge thereof for providing a particular shape of thread.

For these purposes a wheel dresser A is employed having a housing I! vertically and recipcarriage supported upon said base, a work supporting and rotating spindle upon said carriage with an operating gear joined to said spindle, a reversible power shaft having a gear thereon, a rotatable lead screw in threaded engagement with said carriage, and having a gear joined thereto intermeshing with said power shaft gear and said spindle operating gear.

- 2. In a thread grinding machine the combination, a base, a reciprocable work supporting and rotating carriage disposed thereon, a vertically adjustable support on said base, a rotatable thread grinding wheel carried by said support, a wheel dresser adjustably carried by said support, and means pivoted to said support with said dresser riding upon one end thereof and the other end adjustably secured to said base, whereby movement of said support causes a correspondlng proportional movement of said dresser.

3. In a thread grinding machine having a carriage support, a longitudinally reciprocable carriage slidably mounted upon said support with a spindle thereon for rotatably supporting a workpiece, and also having a rotatable grinding wheel adjustably supported adjacent said workpiece; a drive shaft, a cam operable from said drive shaft, a lever pivoted on one end to said carriage support, and cooperatively engaging said cam on its other end, and a fulcrum intermediate the ends of said lever, whereby an intermittent radial motion of said carriage support relative to said grinding wheel is imparted.

4. In a thread grinding machine having a pivotal carriage support, a longitudinally reciprocable carriage slidably mounted upon said support with a spindle thereon for rotatably supporting a workpiece, and also having a rotatable grinding wheel adjustably supported adjacent said work-piece; a drive shaft, a cam operable from said drive shaft, a lever pivoted on one end to said carriage support, and cooperatively engaging said cam on its other end, and a fulcrum intermediate the ends of said lever, whereby an intermittent radial motion of said carriage support relative to said grinding wheel is imparted, said fulcrum being longitudinally adjustable with respect to said lever forregulating the degree of said radial motion.

5. In a thread grinding machine having a base member and a drive shaft joumaled therein and also a grinding wheel; a carriage support pivotally hinged upon its upper edge to said drive shaft, a reciprocable carriage upon said support with a spindle thereon for rotatably supporting a work, and a rotatable cam actuated by said drive shaft and engageable with said carriage support for intermittently imparting a radial motion thereto around said drive shaft axis, relative to said grinding wheel.

6. A thread grinding machine comprised of base, a slide longitudinally adjustable thereon, an angularly adjustable column upon said slide, a housing longitudinally adjustable upon said column, a grinding wheel joumaled thereby, a longitudinally reciprocable carriage supported upon said base, a work supporting and rotating spindle upon said carriage, a grinding wheel dressing'mechanism slidably disposed upon said housing, and compensating means pivoted to saidliousing with one end adjustably secured to said column and the other end supporting said dresser mechanism, whereby upon adjustment of said housing a proportional adjustment is obtained between said dressing mechanism and said grinding wheel.

7. A thread grinding machine comprised of a base, an angularly adjustable column upon said base, a housing longitudinally adjustable upon said column, a grinding wheel joumaled thereby, a grinding wheel dressing mechanism slidably and vertically disposed upon said housing above said grinding wheel, and compensating means pivotally mounted on said housing with one end adjustably secured to said column, and its other end providing a support for said dressing mechanism, whereby upon feeding adjustment of'said housing, said dresser is permitted to descend by its own weight for obtaining a proportional adjustment between said dresser and said grinding wheel.

8. A thread grinding machine comprised of a base, an angularly disposed sub-table pivotally mounted along one of its longitudinal edges above said "base, a longitudinally reciprocable work supporting and rotating carriage upon said subtable, a rotatable grinding wheel adjustably supported above said carriage, an irregularly shaped slide member adjustably secured to said base, a guide member depending from said carriage for supporting the same upon said slide, whereby the carriage throughout longitudinal movement is adapted to be pivoted about the longitudinal edge of said sub-table for transverse movement relative to said grinding wheel, following the contour of said slide member.

9. In a thread grinding machine having a base, a rotatable grinding wheel adjustably supported on said base, and a drive shaft; an angularly disposed carriage support pivotally journaled upon its upper edge to said drive shaft, a longitudinally reciprocable workpiece supporting and larly shaped slide member adjustably secured to said base, a guide member depending from said carriage for supporting the same uponsaid slide,

trolling the movement of said carriage and said spindle, an angularly disposed carriage support pivotally hinged along its longitudinal edge to said drive shaft, and a speed-up transmission between said'power shaft and said drive shaft Y for manually regulating the speed of the latter.

11. In a thread grinding machine having a longitudinally reciprocable carriage with a spindle therein for rotatably supporting a workpiece, and also having a rotatable grinding wheel adjustably supported above said work; a drive shaft, a rotatable lead screw operated by said shaft for actuating said carriage, an angularly disposed carriage support pivotally and hingedly secured along one of its longitudinal edges to said power shaft, means interconnecting said spindle with said-lead screw, a reversing idler interconnected with said lead screw, and manually actuated means for interconnecting said reversing idler with said spindle, whereby the direction of rotation of the work is reversed without effecting the direction of feed of the carriage. p

12. In a thread grinding machine having a base, an adjustable grinding wheel, and a power shaft; an angularly disposed. carriage support pivotally and hingedly joumaled along one of its longitudinal edges to said power shaft, a longitudinally reciprocable work rotating and supporting carriage mounted upon said support, and a plurality of friction minimizingmeans interposed between said carriage and said support.

13. In a thread grinding machine having a drive shaft and an angularly disposed carriage support pivoted along its longitudinal edge to said drive shaft, a longitudinally reciprocable carriage with a spindle thereon for rotatably supporting a workpiece, and also having a rotatable grinding wheel adjustably supported adjacent said work; a drive shaft, a cam shaft operable from said drive shaft, a cam on said cam shaft, a lever pivoted on one end to said carriage support, and cooperatively engaging said cam on its other end, and a fulcrum intermediate the ends of said lever, whereby an intermittent radial motion of said carriage support about said drive shaft relative to said grinding wheel is imparted.

14. In a thread grinding machine having a drive shaft and an angularly disposed carriage support pivoted to said shaft; a longitudinally reciprocable carriage with a spindle thereon for rotatably supporting a workpiece, and also .having a rotatable grinding wheel adjustably supported adjacent said work; a drive shaft, a cam operable from said drive shaft, a lever pivoted on one end to said carriage support, and coopera fulcrum intermediate the ends of said lever,

ro ating carriage upon said support, an irregu.. whereby an intermittent radial motion of said carriage support about said drive shaft relative to said grinding wheel is imparted, said fulcrum being longitudinally adjustable with respect to said lever for regulating the degree of said radial motion.

15. A thread grinding machine comprised of a base, an angularly adjustable column thereon, a rotatable grinding wheel adjustably supported upon said column, a longitudinally reciprocable carriage supported upon said base, a work supporting and rotating spindle upon said carriage, with an operating gear joined to said spindle, a reversible power shaft having a gear thereon, a rotatable lead screw in threaded engagement with said carriage, and having a gear joined thereto intermeshing with said power shaft gear and said spindle operating gear, a reversing idler interconnected with said lead screw, and manually actuated means for interconnecting said reversing idler with said spindle whereby the direction of rotationof the work is reversed without effecting the direction of feed of the carriage.

16. In a thread grinding machine having a base and an adjustable grinding wheel; a carriage support upon said base, a longitudinally reciprocable work rotating and supporting carriage slidably mounted upon said support, and having depending therefrom a recessed shoulder, and interiorly threaded nut, removably disposed within said recess, a stop plate secured to on said column, a reciprocable carriage upon.

said base; ,a work supporting and rotating spindle upon said carriage, with an operating gageable cam operable from said drive shaft, a lever pivoted on. one end to said carriage support, and cooperatively engag g said cam on its other end, and a fulcrum intermediate the ends of said lever, whereby an intermittent radial motion of said carriage support relative to' said grinding wheel is imparted.

. 20. In a thread grinding machine having a pivotal carriage support, a longitudinally reciprocable carriage slidably mounted upon said support with a spindle thereon for rotatably supporting a work-piece, and also having a rotatable grinding wheel adiustably supported adjacent said work-piece; a drive shaft, a cam operable from said drive shaft, a lever pivoted on one end to said carriage support, and cooperatively engaging said cam on its other end, a fulcrum intermediate the ends of said lever, whereby an inter- 'mittent radialxmotion of said carriage support relative to said grinding wheel is imparted, said fulcrum being longitudinally adjustable with respect to said lever for regulating the degree of said radialmotion, and calibrated means adjacent said fulcrum for predetermining the position thereof.

21. In a thread grinding machine having a base member and a drive shaft joumaled therein and also a grinding'wheel; a carriage support pivotally hinged to said drive shaft, a reciprocable carriage upon said support with a spindle thereon for rotatably'supporting a work-piece, and a rotatable cam engageable with said carriage support for intermittently imparting a radial motion thereto around said drive shaft axis, relative to said grinding wheel.

22. In athread'grinding'machine having a longitudinally reciprocable carriage with a spindle thereon for rotatably supporting a work-piece, and also having a rotatable grinding wheel adgear joined to said spindle, a reversible power shaft having a gear thereon, a rotatable lead screw in threaded engagement with said carriage, and having a gear joined thereto inter-meshing with said-power shaft gear and said spindle operating gear.

18. In a thread grinding machine the combination, a base, a reciprocable work supporting and rotating carriage disposed thereon, a column upon said base, a vertically adjustable support upon said column, a rotatable thread grinding wheel carried by said support, a wheel dresser adjustably carried by said support, and means pivoted to said support with said dresser riding upon one end thereof and the other end adjust--- ably secured to said column, whereby movement of said support causes a corresponding proportional movement of said dresser.

19. In athread grinding machine having a carriage support, a longitudinally reciprocable justably supported above said work-piece; a drive shaft, a rotatable lead screw operated by said shaft for actuating said-carriage, an angularly disposed carriage support pivotally and hingedly secured to said power shaft, means interconnecting said spindle with said lead screw, a reversing idler interconnected with said lead screw, and manually actuated means for interconnecting said reversing idler with said spindle, whereby the direction of rotation'of the work-piece is reversed without effecting the direction of feed of carriage slidably mounted upon said support with -a spindle thereon for rotatably supporting a work-piece, an operating gear joined to said spindie, and also having a rotatable grinding wheel adjustably supported adjacent said work-piece; a reversible drive shaft with a plurality of gears thereon, a rotatable lead screw in threaded engagement with said carriage, and having a gear joined thereto intermeshing with said power shaft gear and said spindle operating gear, a disenthe carriage.

23. In a thread grinding machine having a base, an adjustable grinding wheel, and a power shaft; an angularly disposed carriage support pivotally and hingedly joumaled to said power shaft, a longitudinally reciprocable work rotating and supporting carriage mounted upon said support, and a plurality of friction minimizing means interposed between said carriage and said support.

24. In a thread grinding machine having a base, an adjustable grinding wheel, and a power shaft; an angularly disposed carriage support pivotally and hingedly journaled to said power shaft, and a, longitudinally reciprocable work rotating and supporting carriage mounted upon said support.

25. In a thread grinding machine having a base, an adjustable grinding wheel, and a power shaft; an angularly disposed carriage support pivotally and hingedly-joumaled to said power shaft, a longitudinally reciprocable work rotating and supporting carriage mounted upon said support, and manually operable means for reversing the direction of rotation of said power shaft.

26. In a thread grinding machine having a base, an adjustable grinding wheel, and a power shaft; an angularly disposed carriage support pivotally and hingedly journaled to said power shaft, a longitudinally reciprocable work-piece rotating and supporting carriage slidably mounted upon said support, manually operable means for reversing the direction of movement of said carriage, andmeans in spaced relation secured to said carriage for actuating said manually operable reversing means to automatically disen- 10 ing said power shaft.

WILLIAM F. DALZEN.

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