US2731773A

US2731773A - Dressing fixture for grinding machines

Info

Publication number: US2731773A
Application number: US266284A
Authority: US
Inventors: Alfred C Page
Original assignee: Individual
Current assignee: Individual
Priority date: 1952-01-14
Filing date: 1952-01-14
Publication date: 1956-01-24
Anticipated expiration: 1973-01-24

Description

Jan. 24, 1956 A. c. PAGE 2,731,773

DRESSING FIXTURE FOR GRINDING MACHINES Filed Jan. 14, 1952 10 Sheets-Sheet 1 IN V EN TOR.

E- i f Jan. 24, 1956 A. c. PAGE 2,731,773

DRESSING FIXTURE FOR GRINDING MACHINES Filed Jan. 14, 1952 I0 Sheets-Sheet 2 C i 9 INVENTOR. .9 95/62 at Ray Jan. 24, 1956 A. c. PAGE 2,731,773

DRESSING FIXTURE FOR GRINDING MACHINES Filed Jan. 14, 1952 1o Sheets-Sheet s IN VEN TOR.

E4. IIL2II AI Jan. 24, 1956 A. c. PAGE 2,731,773

DRESSING FIXTURE FOR GRINDING MACHINES Filed Jan. 14, 1952 10 Sheets-Sheet 4 fi A24 17%" E, I :Ii! if 24 Hum I HTm 45/ Jan. 24, 1956 A. c. PAGE 2,731,773

DRESSING FIXTURE FOR GRINDING MACHINES Filed Jan. 14, 1952 10 Sheets-Sheet 5 lklwww' Jan. 24, 1956 A. c. PAGE 2,731,773

DRESSING FIXTURE FOR GRINDING MACHINES Filed Jan. 14, 1952 10 Sheets-Sheet 6 IN V EN TOR. flZf/"ed 5. 77456,

Jan. 24, 1956 A. c. PAGE 2,731,773

DRESSING FIXTURE FOR GRINDING MACHINES I Filed Jan. 14, 1952 10 Sheets-Sheet 7 firm W INVENTOR. fiZf/ a 22 6.

4ii wz zzm Jan. 24, 1956 A. c. PAGE 2,731,773

DRESSING FIXTURE FOR GRINDING MACHINES Filed Jan. 14, 1952 10 Sheets-Sheet 8 INVENTOR. fl /nfd 6T Fay-2?.

Jan. 24, 1956 A. c. PAGE 2,731,773

DRESSING FIXTURE FOR GRINDING MACHINES Filed Jan. 14, 1952 10 Sheets-Sheet 9 Vj1/ [d5 H IN V EN TOR. 57 121 [5 7 4 6.

YK LQ Jan. 24, 1956 A. c. PAGE 2,

DRESSING FIXTURE FOR GRINDING MACHINES Filed Jan. 14, 1952 10 Sheets-Sheet 10 INVENTOR. flZf/eq 6 72 6.

United States Patent DRESSING FIXTURE FOR GRINDING MACHINES Alfred C. Page, Detroit, Mich.

Application January 14, 1952, Serial No. 266,284

17 Claims. (Cl. 5195) This invention relates to grinding machines, and more particularly to machines adapted to grind taps and similar products as well as fixtures for dressing and tr'uing the grinding wheel as the product is formed.

In the past dressing fixtures have been provided on grinding machines for grinding special forms, the grinding wheel being alternately engaged with the work and the dressing fixture. For example, the use of crusher rolls has been proposed which are forced into radial contact with the grinding wheel, breaking down the bond between the abrasive particles and imparting an accurate contour to the wheel. Such an arrangement is shown for example in the patents to Polk et al. No. 2,436,527, issued February 24, 1948, and Wilson No. 2,473,670, issued June 21, 1949. The dressing fixtures in such arrangements as are shown in these and similar patents have the disadvantage that they are not integral parts of the machine but are merely attachments for the conventional grinding machine. For this reason they do not increase the fundamental efliciency or usability of the machines but rather serve as accessory devices, increasing the number or" steps necessary in the grinding operation. Another disadvantage of such dressing fixtures is that they are of limited application, and in particular are not adapted for use with machines for grinding objects of circular contour such as taps and similar articles.

It is an object of my invention to overcome the disadvantages of the heretofore proposed types of dressing fixtures and to provide a novel and improved means for grinding taps and similar products and for dressing the grinding wheel, based on the principle of a grinding wheel tangentially movable between the work and the dressing fixture. Such a means is applicable to wheels using diamond dressers and other types of wheel forming devices as well as crusher rolls.

It is also an object to provide an improved grinding machine in which the dressing fixture is an integral part of themechanism, thus resulting in a machine of substantially higher usable potential than has been heretofore possible.

Although the principles of the invention may be embodied in a machine having a straight-line grinding wheel motion, the illustrated embodiment provides a construction wherein the grinding wheel is on a pivoted support and is swingable on a generating radius, thus permitting quick and easy movement between the grinding and dressing positions.

It is a further object to provide a machine of the above character in which the work diameter is predetermined by the position of the wheel forming device and can be changed merely by changing the position of this forming device and in a direction perpendicular to the path of travel of the grinding wheel. In this manner identical work diameters can be produced without the necessity of resetting any portion of the mechanism between articles or during the grinding operation.

It is another object to provide an improved grinding 2,731,773 Fatented Jan. 24, 1956 machine as described above in which the wheel is redressed by moving it toward the forming device, and in which the wear of the forming device may be compensated for by moving it perpendicular to the grinding wheel path of travel. In association with this object, it is within the contemplation of my invention to provide means for automatically moving the grinding wheel toward the forming device after each grinding operation so that the wheel is periodically redressed.

it is also an object to provide a grinding machine as described in which the grinding wheel is movable between a grinding location and a dressing location, and in which means are provided for pre-loading the wheel locating elements so that all working clearances are taken up in the plane passing through the work and the grinding wheel axis. Y

It is a further object to provide a grinding machine of the above character having means for automatically clamping the grinding wheel assembly to prevent axial movement when in the dressing or the grinding locations, this means being preferably combined with locating stop means for the grinding wheel.

It is also an object to provide an improved tap grinding machine which is especially adapted for using the crusher roll type of wheel forming device, the crusher roll being an integral part of the machine and adapted to determine the work diameter of the product.

It is another object to provide a grinding machine as described above having means for automatically cycling the machine elements between the various steps in the grinding and dressing process, so that taps or similar articles can be produced with one pass of the machine.

it is a further object to provide a grinding machine of the above nature having novel and improved driving means for the grinding wheel especially adapted for driving a wheel carried by a movable support or frame, so that each machine is a self-contained unit occupying a minimum of floor space and height.

Other objects, features and advantages of the present invention will become apparent from the subsequent description taken in conjunction with the accompanying drawings.

in the drawings:

Figure l is a side elevational view of a tap grinding machine according to the invention and utilizing a crusher roll type of dressing fixture;

Figure 2 is a front elevational view of the machine, the grinding wheel frame and work table being viewed in the direction of arrow 2 of Figure 1;

Figure 3 is a fragmentary cross-sectional view taken along the line 33 of Figure 1 and showing the feed mechanism for the grinding wheel;

Figure 4 is a view taken along the line 44 of Figure 3 and showing the pawl and ratchet arrangement;

Figure 5 is a view taken partly in cross-section along the line 55 of Figure 3 and showing the striker for the pawl arm;

Figure 6 is a fragmentary cross-sectional view taken along the line 66 of Figure 2 and showing the grinding wheel shaft;

Figure 7 is a fragmentary cross-sectional view taken along the line 77 of Figure 2 and showing the stops and lateral clamping means for the swing frame, as well as the structure of the swing frame and the connecting rod bearing;

Figure 8 is a detailed view of a preferred form of grinding wheel for use with the improved grinding machines in grinding a tapor similar threaded member;

Figure 9 is a cross-sectional view taken along line 9-9 of Figure 2 and showing the work table and work carrying slide, as well as the limit switch for stopping the work spindle;

Figure is a rear elevational view of the motor supporting carriage taken in the direction of the arrow 10 of Figure 1;

Figure 11 is a fragmentary cross-sectional view of the jack shaft between the motor carriage and the swing frame taken along the line 11-11 of Figure 1;

Figure 12 is a detailed cross-sectional view of the oneway clutch on the jack shaft, taken along the line 12-12 of Figure 11;

Figure 13 is a rear elevational view of the cam shaft and crank pin connection, taken in the direction of the arrow 13 of Figure 1, parts being cross-sectioned for clarity;

Figure 14 is a cross-sectional view taken through the crusher roll shaft;

Figure 15 is a detailed cross-sectional view of the brush spindle shaft;

Figure 16 is a schematic view showing the principles of operation of the grinding machine; and

Figure 17 is a circuit diagram of a preferred automatic cycling system for the machine.

Operating principles As suggested previously, the machine of this invention is especially adapted for grinding taps and similar articles, and in the preferred embodiment utilizes a crusher roll type of dressing member. It will be understood however that the principles of the invention could also be embodied in other types of grinding machines and in particular in machines with other types of dressing and forming members, such as diamond dressers.

It will also be understood that while in the illustrated embodiment the grinding wheel is swingable between the grinding and dressing locations, the principles of the invention could be embodied in a machine having a straight-line grinding wheel motion between the two locations, the dressing member being movable perpendicular to the path of the grinding wheel to set the work diameter.

The operating principles of the invention can be seen most clearly in Figure 16. The grinding wheel 21 is rotatably supported on its axis G and this axis supported for swinging movement about a point P spaced a substantial distance from axis G. The work 22 which may be a tap blank or similar article is rotatably supported on a spindle axis S, this spindle axis being set to a predetermined helix angle relative to grinding wheel axis G. The grinding wheel 21 has a preformed peripheral surface for forming the tap threads or the like as will be described later, and the dressing device 23 is supported at a point C which may be the rotary axis of a crusher roll 23, this axis being parallel to axis G. The crusher roll axis C is set at a predetermined distance from the swing axis P and the grinding wheel is swingable between two positions, one in which the wheel has tangential contact with the work 22 and the other in which the wheel tangentially engages crusher roll 23.

When in the grinding position, shown by the dot-dash lines in Figure 16, the grinding wheel is adapted to generate thread forms on the work 22, the work support being provided with means for rotating the work on its axis and giving the work a lead as it rotates. To redress the wheel 21 it is swung back to the crusher roll 23 as shown in the double dot-dash lines and at the same time the grinding Wheel axis G is moved slightly downwardly away from swing axis P. This forces the grinding wheel surface into engagement with the crusher roll, and slow rotation of the grinding wheel and roll will result in a reforming of the grinding wheel contour. It will be noted that since the axis C is held in a constant position with relation to axis P, the generating radius R will always be the same, so that identical work diameters will be pro duced on work 22.

When it is desired to change the work diameter, the

crusher roll axis C is raised or lowered to change its radial distance from axis P. When it is desired to adjust for slight wear in the crusher roll this is also accomplished by raising the roll axis. The method of tangential swinging of the grinding wheel between the crusher roll and work thus affords a most efficient means for grinding thread forms with the least amount of motion of the grinding wheel between its crushing and grinding locations.

General arrangement The general arrangement of the machine is best seen in Figures 1 and 2. The main frame 24 of the machine supports at its lower portion a work table 25 which supports a work carriage 26 in an inclined position. An upright frame 27 surmounts the main frame 24 and a grinding wheel slide 28 is held by a swing frame 29 which is pivotally supported by frame 27. The upright frame 27 also supports a driving motor platform or carriage 30, a cam shaft assembly 31 and a crusher roll frame 32. The grinding wheel swing frame is pivotally supported at the upper portion of the upright frame 27 by a shaft 33 extending between the two sides of the frame, and the location of the shaft is such that the grinding wheel 21 can swing in a path between a grinding location as shown in Figure 1 and a crushing or dressing location in which it is redressed. The swing frame 29 is moved between these positions by a connecting rod 34 which extends through the frame 27 between a crank disk 35 on the crankshaft 36 and a rearward extension 37 of the swing frame 29. The motor carriage 30 is arranged for combined rocking and translatory movement similar to a wheel barrow motion, and in particular is pivotally connected by a jack shaft 38 to the upper portion of the grinding wheel slide 28. The rear portion of the motor carriage 30 is supported on tracks 39 extending rearwardly of frame 27, so that as the slide 28 swings with the swing frame 29 the motor carriage 30 will move correspondingly. The motor carriage 30 supports a grinding speed motor 41 and a crushing speed motor 42, the motor 41 being substantially faster than motor 42, and these motors are connected through jack shaft 38 to the grinding wheel.

As stated previously the work carriage 26 is inclined and the grinding wheel 21 will therefore engage the work tangentially when it is in grinding position. The Work carriage is further provided with a swivel stud 43 for setting the helix angle of the Work axis with relation to the grinding wheel axis. The crusher roll frame 32 is supported for pivotal movement about a shaft 44 at the lower forward portion of the frame 27, the arrangement being such that the crusher roll 23 is movable approximately radially with respect to the swing shaft 33. For this purpose an adjusting handle 45 is provided at the front of the machine frame for raising and lowering the crusher roll frame. A brush 46 is also preferably provided for cleaning the crusher roll 23, this brush being driven by a separate motor 47. The swing frame 29 is provided with stop means, best seen in Figure 7, for holding the grinding wheel in its grinding and crushing positions and preventing lateral play, this stop means preferably comprising a plurality of stop members generally indicated at 43 which alternately engage a lateral stop bar 49 on the swing frame 29.

Means are provided for automatically lowering the grinding wheel 21 a predetermined amount after each grinding operation to enable the wheel to be dressed. This means preferably comprises a pawl and ratchet mechanism generally indicated at 51 which lowers the grinding wheel slide 28 with respect to the swing frame 29 during each return movement from the grinding position to the crushing position. A hand wheel 52 may also be provided for raising and lowering slide 28, for example when the wheel is to be changed. The combined cam shaft and crankshaft 36 is preferably driven by a separate motor (not shown) through reduction gearing 53, as shown in Figure 13, and a plurality of cams on this shaft form part of an automatic cycling system which controls the movement of the grinding wheel between its crushing and grinding locations as well as the rotational speed of the wheel and the movement of the work. This automatic cycling operation is also controlled by a slideable cam bar 54 adjacent the work carriage 26. As the carriage progresses due to the action of lead screw 68, a projection 56 will serve to move the cam bar 54, operating a plurality of switches adjacent the cam bar.

Work table and carriage As stated previously the work table is secured to main frame 24 and has an inclined upper surface 57 which slidably supports the work carriage 26 by means of a rail 58. This rail is adapted to be swiveled about stud 43 to set the correct helix angle of the tap. The work 22 is adapted to be held between centers, and in particular a headstock 59 having a chuck 61 with a center 62, and a tailstock 63 having a center 64, are provided to hold the work. The headstock and chuck are adapted to be rotated by a fluid motor 65 driving a worm wheel 66 on a shaft 67 connected to the chuck 61. The end portion of this shaft is provided with a lead screw 68 which threadably engages a lead nut 69, so that rotation of shaft 67 will cause axial movement of the work. The tailstock 63 is of course slidably mounted in ways 70 to move axially with the work.

As is best seen in Figure 9, the fluid motor 65 is suspended from a bracket 71 by screws 72 adjacent work carriage 26. The work carriage is slidably mounted on rail 58 by means of antifriction bearings 73, and the swivel stud 43 is preferably disposed beneath one of these antifriction connections. The shaft 67 is also preferably provided with a cam projection 74 for operating a switch 75 through a movable arm 76 carrying a roller 77, this switch stopping the work spindle in a predetermined position as will be described later. The cam bar 54 is supported adjacent the work carriage by a plurality of bearing supports 78 and is held in an intermediate neutral position by spring-urged member 79. A group of switches generally indicated at 80 are positioned adjacent the cam bar and a plurality of tapered cam members generally indicated at 81 on the cam bar 54 are adapted to operate these switches by axial movement of the cam bar. Depending from the work carriage is the projection 56 which is disposed between two spaced abutments 82 and 83, the axial travel of projection 56 causing engagement with either of these abutments to operate the cam bar.

Swing frame and slide The swing frame 29 is mounted for simple pivotal or rocking movement with respect to frame 27 by shaft 33, and is of generally elongated shape. This pivotal support is shown best in Figure 3 where it will be seen that the shaft 33 is supported by spaced bearing supports 84 and 85 surmounting the main frame 27 and that a web portion 86 of the swing frame 29 is secured to shaft 33 by bolts 87. As is seen best in Figures 7 and 11, the swing frame 29 has four outwardly facing races 88 extending along its side edges, and these races slidably support the grinding wheel slide 28 which is provided with inwardly facing races 89 cooperating with races 88, and in effect surrounds and encloses the front and rear portions of the swing frame. The lower end of the grinding wheel slide 28 rotatably supports the grinding wheel spindle 90, the lower portion of the slide being of rounded contour and thickened to accommodate the spindle.

The upper end of slide 28 supports a pawl and ratchet mechanism 51 which is used to move the slide with relation to the swing frame 29 and thus feed the grinding wheel for redressing. This movement is accomplished by the rotation of a threaded lead screw 91 rotatably mounted at the upper end of the slide 28 by bearings 92 in an upper slide cap member 93. Lead screw 91 extends downwardly within the slide and threadably engages a lead nut 94 which is rotatably mounted in the swing frame 29. In particular, the nut 94 is mounted at the upper end of a shaft 95 having an enlarged and hollow upper end 96, the lead nut, being fixedly mounted to this rotatable shaft by screws 97. Hollow portion 96 of the shaft is disposed within a radial clearance aperture 98 extending through swing shaft 33, and the shaft 95 is supported by

bearings

99 and 101 for rotation about the longitudinal axis of the swing frame and slide. Bearing 99 is secured in web 86 of the swing frame, and bearing 101 is secured in a lower web 102 of the frame. A plurality of compression coil springs 103 are disposed between the stationary and movable parts of the grinding wheel adjusting mechanism to take up any play or backlash in the moving parts. These springs are preferably disposed adjacent lead screw 91, one end of each spring abutting swing shaft 33 and the other end abutting the underside of cap plate 93 on the grinding wheel slide 28, as seen in Figure 3. These springs 103 continually urge the slide 28 upwardly with respect to the swing frame 29 thus maintaining a definite position of the slide 28 despite any play in the bearings or lead screw connection.

It will be observed that since both lead screw 91 and nut 94 are rotatable in their respective supports either of these members may be utilized to adjust the grinding wheel slide 28 with respect to the swing frame 29. In the preferred embodiment, lead screw 91 is normally used for this adjustment and is connected to an automatic rotating device which steps the lead screw 91 with each swing of the swing frame 29 and slide 28 toward the dressing position. The lead nut 94 may be manually rotated when it is desired, for example, to lift the slide to replace the grinding wheel. For this purpose the lower end of the shaft 95 is connected to a hand wheel shaft 104 by means of a coupling 105. Shaft 104 extends downwardly from web 102 and is provided at its lower end with a bevel gear 106 as seen in Figure 1. This gear cooperates with a bevel pinion 107 which is on a hand wheel shaft 108 rotatably supported at an intermediate portion of the swing frame 29 by a bearing 109 as seen in Figure 7. Shaft 108 extends transversely from the swing frame 29 and an elongated clearance aperture 111 is provided on the front surface of grinding wheel slide 28 through which the shaft 108 extends, as seen in Figures 2 and 7. The hand wheel 52 is fixed to the outer end of shaft 108 so that rotation of the hand wheel will cause longitudinal movement of the slide 28 with respect to the swing frame 29.

The bearing supports 84 and 85 for swing shaft 33 are, as seen best in Figures 2 and 3, mounted atop the upper frame 27 of the machine, the swing frame 29 and slide 28 swinging between the spaced portions of this frame 27. The swing frame 29 is mounted toward one side of shaft 33 (the left side as seen in Figure .2) adjacent bearing84, and this bearing is provided with an. upstanding striker arm 113 which operates the pawl and ratchet mechanism. This striker arm may be adjustably secured to hearing support 84 by means of a slotted connection 114 as seen in Figure 5, and has a rectilinear edge 115 extending upwardly for cooperation with the pawl carriage 116. The bearings 117 are preferably of an antifriction type and the bearing supports are provided with means for taking up any play in the bearing units during operation. This means may comprise one or more annular members 118 surrounding portions 119 of the shaft 33, each member 118 having a rod 121 extending outwardly therefrom. A compression coil spring 122 is disposed around the outer portion of rod 121 and engages a washer 123 secured to the outer end of the rod, the opposite end of the spring resting on the outside bearing support, as seen in Figure 3. The spring 122 will continually urge rod 121 in a radial direction thus exerting a constantxforce on the shaft 33 to take up any play in the bearings.

The pawl and ratchet mechanism for actuating the slide 28 is seen best in Figures 3, 4 and and comprises a ratchet 124 fixed to the upper end of lead screw 91 above cap plate 3. A holding pawl 125 and a driving pawl 126 are adapted to cooperate with the teeth of this ratchet, pawl 125 being pivotally secured at 127 to the cap plate and being urged into engagement with the ratchet by a compression spring 128. Driving pawl 126 is pivoted at 129 to one end of pawl carrier 116, the other end of this carrier being in the path of striker arm 113 when the swing frame is moved from its grinding to its dressing position. Pawl carrier 116 is rotatably supported on the ratchet axis and a tension spring 131 continually urges the carrier in a counterclockwise direction as seen in Figure 4. When the swing frame is moved toward the dressing position the top of the frame will move downwardly as seen in Figure 4, thus causing engagement of carrier 116 with striker arm 113. The subsequent clockwise rotation of the carrier 116 will cause drive pawl 26, which is urged into engagement with the ratchet 124 by a compression spring 132, to rotate the ratchet 124. This movement will cause downward feeding of the slide 28 against the action of springs 103, and the amount of this movement is so chosen as to allow the grinding wheel to be properly redressed. Upon reverse movement of the swing frame 29 holding pawl 125 will prevent further movement of the slide 28.

As stated previously the grinding wheel spindle 91 is rotatably supported by the lower end of slide 28. As is seen best in Figure 6, the spindle is encased in a tubular spindle housing 133 which is held by the slide. The grinding wheel 21 is removably held at one outwardly extending end of the spindle 90 by conventional clamping means 134. The spindle housing 133 has secured at one end thereof a bushing 135 which holds a bearing 136 for one end of the spindle 90, lubricating channels 137 being provided on the spindle 90 within this hearing 136. The opposite end of housing 133 has secured thereto another bushing 133 which holds an antifriction bearing 1319, an additional antifriction bearing 141 being disposed inwardly of bearing 139. The end of the spindle 90 extending outwardly from this end of the housing 133 has secured thereto a sheave 142 driven by belting 143 to rotate the grinding Wheel 21. Means are provided for continually taking up the working clearances in the bearings of spindle 98. This means preferably comprises a supporting ring 144 surrounding an intermediate portion of the spindle 90 and held against rotation by a stud 145. A bushing 1 36 held by the ring 144 engages shaft 90, and the ring 14% is continually urged in one direction by a compression coil spring 147 which abuts the ring 144 and which is held at its other end by an adjusting screw 14% mounted in housing 133. It will be observed that the force of this spring 147 will continually hold the spindle 90 in one direction and therefore take up the working clearances in the bearings.

The stop members 48 and stop bar 49 for stopping the swing frame 29 and slide 23 at predetermined locations in its grinding and dressing positions and for preventing unwanted lateral motion of these parts are seen best in Figure 7, and preferably comprise a pair of dressing position stops 149 and grinding position stops 151 which are mounted in the opposite sides of upper frame 27 These stops cooperate with the opposite ends 152 of bar 49, the bar fitting between each pair of stops on alternate movements of the swing frame 29. Bar 49 is preferably secured to the swing frame by means of the bracket extension 37 which extends rearwardly of the swing frame between the spaced portions of frame 27. This bracket may be held to the swing frame by means of bolts 153 and spacers 154 which extend through an elongated clearance aperture 155 at the rear of the slide 28;

Stops

149 and 151 are preferably of the toggle type and in particular are each mounted for limited pivotal movement by a rounded extension 156 which cooperates with an adjustable block 157 in frame 27. The swing movement of each stop is limited by an adjacent edge 158 of frame 27 and a post 159. A slidable holding member 161 urged outwardly by a spring 162 is disposed within each stop element and cooperates with its corresponding post 159 to hold the stops in position to receive the bar 49. Each stop has an apex portion 163 and an adjacent shoulder 164, and the bar 49 is of such length that it is gripped between the apices of each pair of stops and is held against movement by the shoulders 164. The overcenter operation of these stops will be apparent from examination of Figure 7, where it will be seen that the swing frame 29 is securely held in either of its operative positions by these stops.

Grinding wheel and driving means It may be well here to describe the cooperation of the grinding wheel 21 and the tap blank in the illustrated embodiment of the invention. It will be understood that this type of grinding wheel is merely illustrative of other types which could be used for the grinding operation, the particular type of grinding wheel not affecting the principles of the invention. The grinding wheel is provided with a shield 165 secured to one side of the slide 28 and to one end of stop bar 49, as seen in Figure 7, and the wheel extends through the open lower end of this shield. As seen in Figure 8, the wheel is provided with a plurality of V-shaped ribs 166 which form the roughing ribs for grinding the threads 167 on the tap blank 22. In spaced adjacent relation with these roughing ribs is a finishing rib 163 of slightly greater diameter, and a face grinding surface 169 is disposed at the end portion of the wheel. in operation, the tap blank is set to the correct helix angle by swiveling the work carriage in the manner previously described. (In Figure 8 the Work is shown as having a zero helix angle in order to more clearly show the thread contours.) in this connection it should be noted that the axis of the swivel stud 43 is preferably aligned with the center of finishing rib 168 so that the tap blank will swivel about this finishing rib as a center. The roughing ribs 166 engage the tap blank 22 at the start of grinding, and after the work has made more than one revolution the threads are completely roughed out. The grinding speed is then increased and the finishing rib 168 traverses the full length of the tap bringing it to size. At the same time the flat at the apex of the thread is produced by the surface 16?. Of course the swing frame 29 is held stationary all during this grinding operation by the means described above. After the grinding is completed the swing frame 29 is moved back to the dressing position and the completed tap is removed from the work.

As indicated previously the driving motors for the grinding wheel are mounted on a movable carriage or platform 30 mounted at the top of frame 27 and having a pivotal connection to the slide 28 by means of jack shaft 38. As is seen best in Figures 1 and 10, the rear portion of platform 30 is supported by a pair of wheels 171 which roll on tracks 39 extending rearwardly from frame 27 in cantilever fashion. This gives a wheelbarrow motion to platform 30 when the swing frame 29 is rocked.

Grinding speed motor 41 and crushing speed motor 42 are mounted on platform 30 and are connected to the grinding wheel through jack shaft 38. It will be understood that although in the illustrated embodiment-the grinding wheel 21 rather than crusher roll 23 is driven at a slow speed during the crushing operation, the prining on either side of bearing 172. It will be noted that this arrangement permits both the adjusting movement of the slide 28 and the swinging movement of the entire swing assembly without disturbing the motor connections. The jack shaft 38 is supported in shaft housing 173 by a pair of oppositely disposed antifn'ction bearings 175 having seals 176. The connection from the fast speed or grinding speed motor 41 comprises belting 177 extending between the motor sheave 178 and a driven sheave 179 secured to a reduced portion 181 of shaft 38. The slow speed or crushing speed motor 42 is connected to the shaft by a chain 182 extending between driving sprocket 183 and a driven sprocket 184 on an outer reduced portion 185 of the jack shaft 38. This sprocket 184 is not connected directly to the shaft 38 but is secured to an annular element 186 which comprises the outer member of a one way or overrunning clutch, the inner member 187 of which is keyed directly to shaft portion 185 as seen in Figure 12. Element 186 is rotatably supported by an antifriction bearing 188 and an annular insert 189 within element 186 engages the spring pressed roller elements 191. When slow speed motor 42 is running but high speed motor 41 is stopped the jack shaft 38 will thus be driven at the slow speed, say 100 R. P. M. However, when the high speed motor 41 is started the

clutch elements

186 and 187 will be disengaged and the jack shaft will be driven at the grinding speed which may be for example 1800 R. P. M.

The opposite end of shaft 38 has a reduced portion 192 to which is secured a sheave 193. The belting 143 connects this sheave with the grinding wheel shaft sheave 142. It will be observed that the arrangement is such that the belting is at no time subjected to stretching forces or slackened during movement of the swing frame, since the distance between jack shaft 38 and grinding wheel spindle 90 remains constant during operation.

Crusher roll assembly As stated above the crusher roll 23 is mounted for bodily movement relative to the frame of the machine by means of a crusher roll carrier frame 32 pivotally connected to frame 27 at 44. This crusher roll carrier frame 32 preferably also supports a wire brush 46 which is in adjacent relation with the crusher roll 23 and which is driven by motor 47 to clean this roll during operation. The frame 32 has a forward extension 194 which extends within the confines of the inclined work platform 25 as seen in Figure 1. This extension has a boss 195 which extends downwardly therefrom and a vertically disposed adjusting screw 196 is adapted to engage this boss for moving the frame. Adjusting screw 196 is threadably mounted in a lead nut 197 which is secured to the machine frame, and a worm wheel 198 slidably keyed to the lower end of shaft 196 is rotatable by a worm 199. Hand wheel 45 at the front of the machine is adapted to rotate worm 199 through shaft 201, so that the crusher roll 23 may be lifted or lowered by means of hand wheel 45 to determine the work diameters in accordance with the principles of operation already described. If desired the forward end of frame extension 194 may be provided with an anvil 202 for operating an indicator 203 at the front of the machine, this indicator showing the operator the position of the crusher roll 23. The frame 32 may also support idler wheels 204 for guiding the belt 205 between the brush motor 47 and brush 46.

The mounting means for the crusher roll 23 and the brush 46 are shown in Figures 14 and 15. Crusher roll spindle 206 is rotatably supported by a spindle housing 207 having antifriction bearings 208 mounted therein. The crusher roll 23 is removably keyed on end portion 209 of the shaft by clamp 211, a dust cover 212 being dis posed inwardly of the roll. Since as indicated above the crushing operation may be accomplished by means other than driving the grinding wheel 21 a chain sprocket 213 is shown as secured at the opposite end 214 of the crusher roll spindle 206 although in the illustrated enn bodiment this sprocket 213 is not used. The brush spindle 215 is shown in Figure 15 and is rotatably supported on the frame 32 by means of bushings 216. The chain sprocket 217 on this spindle is continuously driven by the chain 205 from brush motor 47.

Electrical control system From the above description of the grinding machine and its principles of operation it will be apparent that the machine may be operated either manually or automatically in a number of different ways, depending upon the type of job. With any of these methods for controlling the machine its principles of operation will remain the same since they depend solely upon the method and structural characteristics described above. For illustrative purposes a preferred electrical control system for automatically cycling the machine between its grinding and dressing operations is shown in Figure 17.

Before describing the details of this system the structure of the cam shaft and swing frame operating shaft assembly 31 should be noted. This assembly is mounted on a rear platform 218 of the frame 27 and comprises the reduction gearing 53 driven by a cam shaft and swing frame driving motor not shown in Figures 1 to 16 but designated as 219 in the schematic control diagram (Figure 17). Motor 219 drives the reduction gearing through an overrunning clutch 220 having a sheave 221, so that reversal of the motor from its driving direction will instantaneously stop the cam and swing frame crank shaft 36 extending laterally from both sides of the reduction gear housing. The combined cam and crank disk 35 is secured to one end of shaft 36 and has a crank pin 222 extending therefrom, and connecting rod 34 extends between this crank pin and the bar 49 which is secured to swing frame 28. The periphery of disk 35 is further provided with a pair of cams 223 and 224 apart which serve as cycling cams. Shaft 36 is further provided with

cam disks

225 and 226 which also serve to operate switches during the cycling operation. Of these, cam 225 is secured to the periphery of disk 35, while cam 226 is mounted on the opposite side of shaft 36 by means of a cam disk 227. This cam disk may also support an additoinal cam 228 for operating another switch in the control system if desired. The group of switches operated by these cams are generally designated at 229 in Figure 1 and are supported rearwardly of frame 27 above the cams. In particular cams 223 and 224 operate switch S1 which controls the motor 219, cam 225 operates relay control switch S2 and cam'226 controls grinding wheel control switch S3.

The cycling operation is also controlled by reciprocat ing cam bar 54 which as already described is held in neutral position by spring urged member 79 and is operated by movement of the work carriage 26 through a lost-motion connection comprising projection 56 and stops 82 and 83. Referring to Figure 2, the cams 81 on cam bar 54 control the plurality of switches 80. In particular, a pair of

cams

231 and 232 control an over-run protection switch S4, cam 233 controls a grinding stop switch S5, cam 234 controls a sustained contact break switch S6, cam 235 controls a slow down return switch S7 and cam 236 controls a stop reverse switch S8. For proper operation these switches are operated at different portions of the movement of cam bar 54. For

example cams

234 and 235 may be adapted to operate switches S6 and S7 respectively after movement of the cam bar in opposite directions. Cams 233 and 236 are adapted to operate switches S5 and S8 respectively after ,5 movement, and

cams

231 and 232 are adapted to operate the over-run protection switch S4 after movement in either direction.

The circuit diagram of Figure 17 shows schematically the grinding speed motor 41, the crushing speed motor 42 and the cam shaft and swing frame driving motor 219 in the upper right portion of the diagram, and also shows the

cam disks

35, 225, 226 and the cams of cam bar 54. The fluid motor 65 which actuates the work spindle 67 as well as the work carriage 26 is controlled by hydraulic valves V1 and V2 shown schematically in the upper right portion of the diagram, valve V1 controlling the direction of movement of the work and carriage and valve V2 controlling the speed. Power is supplied to the motors through power supply conduits 237 which may comprise a 220 volt three phase circuit. A transformer 238 is Provided for supplying a lower voltage, say lit) volts, for the control portions of the system.

The system is provided with a starting switch S9 and a stop switch S14 which control the movement of a primary relay R1 for supplying power to the system. This relay allows power to be supplied to relays R2 and R3 which control the reverse and driving direction respectively of cam motor 219, relays R4- and R5 for controlling the driving and reverse directions respectively of grinding speed motor 41, and relay R6 which controls crushing speed motor 42. The operation of these relays is controlled by the various switches as is hereinafter described, and these switches also control the movement of relays R7 and R8 for controlling the reverse and forward positions respectively of valve V1, timer relay TRl for conwork spindle stop switch 75 which is operated by work spindle cam 74 as previously described.

Perhaps the system may be understood best by a description of a complete cycle of events during a grinding and dressing operation. Starting from an initial condition in which a grinding and dressing operation has just been completed but the work carriage has not been returned yet to its starting position, the cams 223226 will be in an approximate position as shown in Figure 17. It will be noted that when in this position switch S1 is in its lower position, and that

cams

225 and 226 each have two dwell portions of about 180, with switch S2 in its upper position and switch S3 in its lower position. it will also be observed that cam bar 54 is in its intermediate neutral position with switches S5--S8 in the positions shown in Figure 17, and that enabling relay R9 is in its left-hand or deenergized position. The machine is started by first pressing starting switch S9 which closes primary relay R1 and its holding circuit. This will result in starting crushing speed motor 42, the circuit through this motor being completed by the energization of relay R6 through timer relay TR2, which in turn is energized through switch S3. Cam shaft motor 219 will also be started in reverse by the energization of relay R2 through deenergized relay R3, but this will cause no cam shaft movement because of one-way clutch 220. To start the cycle switch S1]. is closed momentarily, operatingly relay R7 by a circuit through switch S4, relay R7 being thereafter held by current flowing through switch S8. Current is thus supplied to the reverse side of valve V1 and also through relay R9 and switch S7 to the fast side of valve V2. The work carriage 26 will therefore move in a reverse direction at fast speed. It will be observed that during this interval cam shaft motor 219 is still in reverse so that motor 42 remains running, and there is no movement of the swing frame.

Near the end of travel of the work carriage 26, the switch S7 is operated by cam 235 and current is supplied to the slow side of valve V2, slowing down the rotation of fiuid motor 65. At the end of the work carriage stroke switch S8 is moved to its lower position, breaking the circuit to relay R7 and stopping the fluid motor 65. At the same time current will pass from switch S3 through relay R9 to energize cam motor drive relay R3. This decnergizes relay R2 and starts driving rotation of motor 219 and control cams 223-226, and this rotation will continue until the holding circuit for relay R3 through switch S1 (which moves to its upper position upon initial rotation of the cam shaft) is again broken. Rotation of the cam shaft also moves the grinding wheel away from the crusher roll and toward the work. As it moves toward the work grinding wheel control switch S3 is moved to its upper position deenergizing timer relay TR2 and energizing relay R4, and the motor 41 will drive the wheel at grinding speed while crushing speed motor'42 comes to a halt. Simultaneously switch S2 will be closed to energize R9.

When the grinding wheel reaches its grinding location switch S1 is again moved to its lower position, this time by cam 224, and the holding circuit to relay R3 is broken stopping the movement of the cam shaft and energizing relay R2 to drive motor 219 in reverse. Current will pass through switch Si, relay R9 and switch S6 to energize relay R8, the holding circuit for relay R3 being closed through switches S5 and '75 in parallel. Current from relay RS will flow to the forward side of valve V1 and to the slow side of valve V2, the latter through timer relay TRl which is also energized by the closing of R8 but is not immediately tripped. This will start the work and carriage for the rough grinding operation, and after a predetermined interval timer relay TRl will trip shifting valve V2 from slow to fast to speed up the work for finish grinding.

Near the end of the finish grinding operation switch S6 is opened by movement of the work carriage 26; however the current flowing through switch S5 will keep relay R8 closed until switch S5 is moved to its lower position by cam 233. When this occurs the fluid motor will stop with the work spindle at a predetermined position, since switch 75 is in parallel with switch S5. Current from switch S5 will thereafter flow through relay R9 to cam motor drive relay R3 and the cams 223226 will begin again to rotate. This will move the grinding wheel away from the work and will raise switch S1, lower switch S3, and open switch S2. The operation of switch S3 will deenergize relay R4 and energize relay R5 for a time interval determined by timer relay TR2 which is also energized through switch S3. The grinding speed motor 41 will therefore be reversed and thus brought to a stop. After a predetermined interval timer relay TR2 will trip deenergizing relay R5 and energizing crushing speed m0- tor 42 to begin rotation of the grinding wheel at crushing speed for the dressing operation. Opening of switch S2 has meanwhile deenergized relay R9, and the system will remain in this condition until push button S11 is operated again to start another cycle.

While it will be apparent that the preferred embodiment of the invention herein disclosed is well calculated to fulfill the objects above stated, it will be appreciated that the invention is susceptible to modification, variation and change without departing from the proper scope or fair meaning of the subjoined claims.

What is claimed is:

1. In a device of the class described, a work spindle adapted to rotatably support the work, a grinding wheel spindle, a swinging frame pivoted on a swing axis and having a longitudinal track thereon, a slide supported on said track and holding said grinding wheel spindle, a dressing element adjacent said work spindle, the grinding wheel spindle being movable about said swing axis between a grinding position adjacent said work spindle and a dressing position adjacent said dressing element, and means for moving said slide on said frame, said means being actuated by movement of the grinding wheel spindle from said grinding position to said dressing position, whereby said grinding wheel spindle is fed toward said dressing element.

2. The combination according to claim 1, further provided with means for adjustably holding said dressing element in different radial positions with respect to said swing axis.

3-. In a device of the class described, a work spindle adapted to rotatably support the work, a grinding wheel spindle, a swinging frame pivoted on a swing axis and having a longitudinal track thereon, a slide supported on said track and holding said grinding wheel spindle, a dressing element adjacent said work spindle, the grinding wheel spindle being movable about said swing axis between a grinding position adjacent said work spindle and a dressing position adjacent said dressing element, means actuated by swinging movement of said frame toward said dressing element for feeding said slide toward said dressing element, and resilient means between said frame and said slide resisting said feeding movement.

4. In a device of the class described, a work spindle adapted to rotatably support the work, a grinding wheel spindle, a swinging frame having a longitudinal track thereon, a means supporting said frame for movement about a swing axis, a slide supported on said track and holding said grinding wheel spindle, a dressing element adjacent said work spindle, the grinding wheel spindle being movable about said swing axis between a grinding position adjacent said work spindle and a dressing position adjacent said dressing element, and means for moving said slide on said frame when the grinding wheel spindle is moved from said grinding position to said dressing position, said means comprising a rotatable lead screw connection and pawl and ratchet means for rotating said connection upon swinging movement of said grinding wheel spindle.

5. The combination according to claim 4, further provided with manual means on said slide for rotating said lead screw connection independently of said pawl and ratchet means.

6. In a machine having a grinding wheel spindle, a work spindle adapted to rotatably support the work, a dressing element adjacent said work spindle, a swing frame, a slide on said frame and holding said grinding wheel spindle whereby the grinding wheel is movable between a grinding position adjacent said work and a dressing position adjacent dressing element, and holding means for retaining said grinding wheel in its said positions, said holding means comprising two pairs of clamps, each pair being engageable with opposite sides of said slide in the grinding and dressing positions to prevent lateral movement thereof.

7. In a grinding machine, a work spindle adapted to rotatably support the work, a grinding wheel spindle, a dressing element adjacent said work spindle, a swing frame, a slide on said frame and holding said grinding wheel spindle whereby the grinding wheel is movable between a grinding position adjacent said work and a dressing position adjacent said dressing element, holding means for laterally retaining said grinding wheel in its said positions comprising two pairs of over-center clamps, and means for adjusting the lateral positions of said clamps.

8. In a grinding machine, a work spindle adapted to rotatably support the work, a dressing element adjacent said work spindle, a grinding wheel spindle adjacent said work spindle, a swingable frame, a slide on said frame and supporting said grinding wheel spindle whereby the grinding wheel is swingable between a grinding position and a dressing position, driving means for said grinding wheel spindle, a movable support for said driving means comprising a platform having a pivotal connection at one end with said slide, and means for movably supporting the other end of said platform.

9. In a grinding machine, a work spindle adapted to rotatably support the work, a dressing element adjacent said work spindle, a grinding wheel spindle adjacent said work spindle, a swingable frame, a slide on said frame and supporting said grinding wheel spindle whereby the grinding wheel is swingable between a grinding position and a dressing position, driving means for said grinding wheel spindle, a movable support for said driving means comprising a platform having a pivotal connection at one 14 end with said slide, and a jacket shaft at said pivotal con nection for transmitting the movement of said driving means to said grinding wheel spindle.

10. In a grinding machine, a work spindle adapted to rotatably support the work, a dressing element adjacent said work spindle, a grinding wheel spindle adjacent said work spindle, a swingable frame, a slide on said frame and supporting said grinding wheel spindle whereby the grinding wheel is swingable between a grinding position and a dressing position, driving means for said grinding wheel spindle including a relatively high speed grinding motor and a relatively low speed dressing motor, mounting means for said motors comprising a platform pivotally connected to said slide, a jack shaft at said pivotal connection and having a driving connection with said grinding wheel spindle, a direct driving connection between said grinding motor and said jack shaft, and a driving connection including a one way clutch between said dressing motor and said jack shaft.

11. In a grinding machine, a work spindle adapted to support the work for rotational and axial movement, a crusher roll adjacent said work spindle, a grinding wheel spindle swingably supported on a swing axis adjacent said work spindle and said crusher roll, whereby the grinding wheel is movable between a grinding position in tangential engagement with the work and a crushing position in tangential engagement with the crusher roll, means responsive to swinging movement of said grinding wheel spindle toward said crushing position for moving said grinding wheel spindle radially away from its swing axis, means for adjustably holding said crusher roll in various radial positions with respect to said swing axis, and means including a crank shaft for swinging said grinding wheel spindle between its said positions.

12. The combination according to claim 11, further provided with driving means for rotating said grinding wheel spindle at a relatively fast speed when in its grinding position and at a relatively slow speed when in its crushing position.

13. In a grinding machine, a work spindle adapted to support the work for rotational and axial movement, a crusher roll adjacent said work spindle, a grinding wheel spindle swingably supported on a swing axis adjacent said work spindle and said crusher roll, whereby the grinding wheel is movable between a grinding position in tangential engagement with the work and a crushing position in tangential engagement with the crusher roll, means responsive to swinging movement of the grinding wheel spindle towards its crushing position for moving said grinding wheel spindle radially away from its swing axis, and means for adjustably holding said crusher roll in various radial positions with respect to said swing axis.

14. In a grinding machine, a work spindle adapted to rotatably support the work, a dressing element adjacent said work spindle, a grinding wheel spindle swingably supported adjacent said work spindle and said dressing ele ment, whereby the grinding wheel is swingable between a grinding position in tangential engagement with said work and a dressing position, and means for moving said grinding wheel support between its said positions, said means comprising a rotatable crank shaft, a crank connection between said shaft and said grinding wheel support, driving means for said crank shaft, automatic cycling means for moving said grinding wheel spindle between said positions, said cycling means including a cam rotatable with said crank shaft, and switch means operated by said cam and controlling said driving means.

15. In a grinding machine, a work spindle adapted to support the work for rotational and axial movement, a crusher roll adjacent said work spindle, a grinding wheel spindle swingably supported on a swing axis adjacent said work spindle and said crusher roll, whereby the grinding wheel is movable between a grinding position in tangential engagement with the work and a crushing position in tangential engagement with the crusher roll, means for moving said grinding wheel spindle radially away from its swing axis while moving from said grinding position to said crushing position, means for adjustably holding said crusher roll in various radial positions with respect to said swing axis, means including a crank shaft for swinging said grinding wheel spindle between its said positions, driving means for said work spindle, automatic cycling means for operating said driving means, said cycling means including a cam operated by the axial movement of said Work spindle, and a switch operated by said cam and controlling said work spindle driving means.

16. In a device of the class described, a work spindle adapted to rotatably support the work, a grinding wheel spindle adjacent said work spindle, a dressing element adjacent said work spindle, swingable supporting means for said grinding wheel spindle pivoted on a swing axis whereby the grinding wheel is adapted to move into alternate tangential engagement with the work and the dressing element, a frame adapted to support the dressing element, said frame being pivotable about an axis parallel to said swing axis, means for adjustably holding said frame in various angular positions whereby the dressing element may be adjusted substantially radially with respect to the swing axis, adjusting means for moving said grinding wheel spindle radially outwardly with respect to its support axis so as to engage said dressing element, and means for holding the grinding wheel in said outwardly adjusted position when moved from said dressing element to the work, whereby the grinding wheel tangentially engages the work.

17. The combination according to claim 16, said dressing element comprising a crusher roll, and cleaning means for said roll rotatably supported by said frame.

References Cited in the file of this patent UNITED STATES PATENTS 1,624,211 Bryant Apr. 12, 1927 1,633,051 Trbojevich June 21, 1927 1,659,227 Wildhaber Feb. 14, 1928 1,899,654 Ward Feb. 28, 1933 2,028,315 Bruhl et al Jan. 21, 1936 2,135,202 Scrivener Nov. 1, 1938 2,277,213 Dalzen Mar. 24, 1942 2,350,897 Iellis June 6, 1944 2,377,241 Kavle May 29, 1945 2,477,418 Polk July 26, 1949 2,557,166 Ziegler June 19, 1951 FOREIGN PATENTS 202,134 Great Britain Aug. 16, 1923