US2439360A - Infeed for grinding machines - Google Patents

Description

April 6, 1948. w. 1.. BROWN INFEED FOR GRINDING MACHINES Filed Sept. 28, 1946 2 Sheets-Sheet 1 I lllilllll l I IIHIH H '16 WLLLLam L.Dr'own. aw/fi'v g Patented Apr. 6, 1948 mraap FOR GRINDING MACHINES William L. Drown, Paxton, Masai, assignor to Norton Company, Worcester, Mass., a corporation of Massachusetts Application September 28, 1946. Serial No. 700,035

13 Claims. (Cl. 51-2) The invention relates to grinding machines and more particularly to cylindrical grinding machines.

One object of the invention is to provide an improved cylindrical grinding machine for grind.- ing cylindrical surfaces wherein the finished size may be automatically'controlled with great accuracy. Another object is to improve the machine of U. S. Patent No. 2,267,391 to Astrowski.

Another object of the invention is to. provide a readily controlled automatic apparatus for rapidly moving the grinding wheel and the work relatively toward and away from each other. Another object is to provide automatically controlled and variable slow speed grinding wheel infeed during the grinding operation after rapid relative approach of the wheel and the Work with automatic separation of the wheel and the work when desired work size is reached. Another ob ject is to provide smooth grinding infeed action of the grinding wheel relative to the work at various grinding infeed speeds with or without automatic work size .control within extremely fine limits of accuracy. Another object is to provide increased production in finish grinding. Another object is to provide apparatus of the character indicated which may be economically manufactuned and compactly assembled on a standard grinding machine and which will give accurate and dependable operation over a longperiod of time.

Other objects will be in part obvious or in part pointed out hereinafter.

The invention accordingly consists in the features of construction, combinations of elements, and arrangement of parts, as will be exemplified in the structure to be hereinafter described, and

the scope of the application of which will be indicated in the following claims.

In the accompanying drawings, in which is shown one of many possible embodiments of the mechanical features of this invention,

Figure 1 is a longitudinal sectional view of the .apparatus of the invention mounted upon the wheel feed shaft;

Figure 2 is an end view of the apparatus; Figure 3 is a vertical sectional view of the apparatus of the invention and associated mechanism together with a wiring diagram and a fluid when size is reached.

i 2 i chine has a work table upon which is mounted a. headstock and a tailstock to hold a cylindrical work piece and rotate it against the grinding wheel for cylindrical grinding. Such a machine also has fluid pressure means for rapid infeed and retraction and for normal grindmg inieed and slow grinding infeed.

The terms rapid infeed and retraction as used herein mean positioning of the grinding wheel relative to the work preparatory to grinding and, retracting it rapidly from the work when gr.nding is completed. The term normal grinding infeed" means feeding the wheel against the work during rough grinding, and the term "slow grinding infeed" means feeding the wheel ag'a.nst the work for the-final and finishing cuts.

According to the present invention additional fluid pressure means hereinafter described are provided whereby after the wheel slide has rapidly approached the work piece and is ready to grind, a very finely controlled smooth and accurate slow grinding infeed is provided with uniformity within close tolerances and with automatic stopping of the grinding ini'eed and rapid retraction of the wheel slide relative to the work on on the V-ways-IZ which in tum rotatably supports a grinding wheel I3. The base II) also supports a longitudinally movable work supportng table (not shown) which is arranged to slide on ways.

Work rotation Grinding wheel drive mechanism The grinding wheel I3 is mounted on. a spindle l5'which is joumalled in bearings in the top of the wheel slide Ii, and it is driven by any convenient source of power such .as an electric motor I1 whichmay be mounted on the wheel slide ii to drive a pulley l8.m0unted on the motor shaft iii, a belt 20 and a pulley 2|:on the wheel spindle l5.

cylinder 60 which is also slidable upon the sleeve I Grinding wheel rapid infeed mechanism A half nut 25 depending from the under side of the wheel slide II and fastened to it engages a threaded portion 25 of a feed screw 21 which is rotatably connected to an enlarged portion 28 of a longitudinally slidable feed shaft 23 in bearlugs 30 in the base II) of the machine. wheel (not shown) on the front of the machine is connected to turn the feed screw 21. Rotation of the hand wheel in one direction feeds the wheel slide I I and grinding wheel I3 into the work, and

in the other direction retracts the wheel slide II. For rapidly moving the grinding wheel I3 to and from a grinding position, fluid pressure means are provided comprising cylinder 3| which is either formed as an integral part of the base I or fixedly mounted thereon. The shaft is aligned with the axis of the cylinder and serves as a piston rod. A piston 35 is slidably mounted within the cyllnder 3| and is supported on a reduced end portion 36 of the piston rod 29. An end thrust bearing 38 is interposed between a shoulder 39 on the rod 36 and one end of the piston35 and a second and thrust bearing 40 is interposed between the other end of the piston 35 and a nut 4| on the rod 36. It will be apparent that when the piston is moved endwise, it will transmit a feeding movement to the grinding wheel I3 through the rod 29, its enlarged portion 28. the feed crew shaft 21 and half nut to move the wheel slide II. The feed screw 21 is arranged so that it may be rotated relative to the piston so that the operator, by manual rotation of the feed screw 21 may readily adjust the position of the grinding wheel I3 relative to the fluid pressure mechanism.

Grinding infeed mechanism A fluid pressure actuated piston and cylinder A hand mechanism 50 is provided in alignment with and assembled about an extended portion 5| of the feed shaft 29 for accurate control of grinding wheel infeed during the grinding operation and positive stopping upon grinding of the work piece to desired size.

A sleeve 55 is slidably mounted upon the extended portion 5| of the feed shaft 23. A piston 56 is mounted upon the sleeve 55 and held against a shoulder 51 on the sleeve 55 by means of a nut Slidably mounted over the piston 55 is a 55 by means of packed fluid pressure tight holes GI and 62 in the cylinder heads 63 and 66. Near the inner end of the sleeve 55 a threaded collar 65 having a split locking portion 61 is adjustably mounted on a threaded portion of the sleeve 55. On a threaded portion 69 on the outer end of the shaft 5| is adjustably mounted a collar l0 which has a split locking portion II. A pair of bell crank arms I5 and I6 pivot about shafts i1 and '18 mounted in bosses I9 and 80 which are integral with the base I0 of the machine. The bell crank arms 15 and 16 have bearing surfaces 85 and 86 on the short ends thereof which ride against the face 87 of collar 66. On the ends of the long arms 88 and 89 of the bell crank arms I5 and T6 are rotatably mounted a pair of cam followers 90 and iii. These make contact with an outside conically shaped cam surface portion I00 of the cylinder 60.

When fluid pressure in the main cylinder 3| drives the piston 35 and hence the wheel slide II forward for rapid infeed, the collar 10 finally makes contact withthe outer end ml of the sleeve 55. The sleeve 55 cannot go any further in because the face 81 of collar 56 is riding against surfaces 85 and 86 of the bell crank arms 15 and I6 which are in turn held in position by the cam followers 00 and BI upon the cam surface I00 of the cylinder 50. However when fluid pressure is introduced into the left hand portion of cylinder 60 and exhausted out of the right hand portion. the cylinder 60wil1 move to the left along sleeve 55 and piston 56. This allows the cam followers 90 and 0| to roll down the cam surface I00 toward each other which in turn imparts a slight movement of bearing surfaces 85 and 56 to the left thus allowing collar 66 sleeve 55, collar 10, feed shaft 5| and wheel slide II to move very slightly to the left for a very fine grinding infeed while the grinding wheel is cutting the work. While a full head of fluid pressure may be maintained .in the main cylinder 3| and cam actuating cylinder 60 all during the rapid infeed and grinding infeed cycle, it may be seen that rapid infeed is changed to slowgrinding infeed when collar I0 makes contact with sleeve 55 and slow grinding infeed may be controlled by metering oil out of cylinder 50. A positive stop is provided when work size is reached by instantly reversingthe flow of fluid pressure in both cylinders 3| and 60, as will be more fully explained.

Fluid pressure control A fluid pressure control valve I05 is provided to regulate the admission of fluid to cylinders 3| and 50. This valve is preferably of the balanced piston type having a valve stem I06 and a plurality of valve pistons I01, I08, and I09 which are slidably mounted in the valve I05; The ports in the valve I05 are so arranged that fluid from a reservoir H2 is forced by a pump 3 through a conduit II4 into a valve chamber II5. As the valve stem I06 is shifted from one extreme to the other extreme position, the fluid flow may be changed from one side of piston 35 to the other to reverse the direction of movement of the wheel slide, and from one side of piston 56 to the other to reverse the direction of movement of cylinder 50. In the construction shown, with the valve stem I05 positioned to the left against spring II8, fluid under pressure enters through valve chamber 5 and goes to the right side of piston 35 through passage I20. It may also enter cylinder 60 at the left side of piston 56 through pipe I2I and check valve I22. Fluid is exhausted from the left side of piston 35 through passage I25, valve chamber I26 and back into reservoir 2 through pipe I2I, hand adjusted valve I28, and also through pipe I29 and solenoid operated valve I30 which is kept normally open by spring I3I.

Fluid is exhausted also from the right side of piston 56 through pipe I35, solenoid operated metering valve I35, pipe I3! and back to the reservoir II2 by way of passage I25, as described. This is the main valve setting for rapid and normal grinding infeed, to the left as shown. With rapid infeed to position the wheel, it is desirable to slow the action down somewhat just before collar I0 makes contact with sleeve 55 so as to avoid jarring of the cam actuating mechanism. To this end the solenoid operated valve -valve I28 to slow down the infeed action just before collar I0 makes contact with sleeve 55.

The movement of cylinder 60 is delayed while piston 35 is operated for rapid inieed because solenoid operated metering valve I88 is normally almost closed to allow only a very fine stream of fluid to pass through it. It has a stem I40 having a wedged slot I, which when it is normally positioned to the left as shown, meters fluid through it at a slow rate which is adjustable by set screw I42 to allow only a very slow grinding infeed by slow cam action of cylinder 80 to the left. When valve stem I40 is to the right, fiuid is metered at a more rapid rate for normal grinding infeed. Positive stopping of inieed is instantaneous and retraction oi the grinding wheel ,is immediately brought about by reversing the flow of fluid through the piston and cylinder assemblies by reversing solenoid operated valve I05.

During retraction of both the main piston 85 and the cam actuating cylinder 80, fluid delivered from the reservoir II2 by pump II8 under pressure passes through valve chamber II5, passage I25 to the left side of piston 85. It also passes through line I31 and a check valve I48 which is provided in a shunt pipe I44 across valve I38 between lines I 31 and I85, and into cylinder at the right side of piston 58 under full head to retract cylinder to rapidly to .the right to its initial starting position. Cylinder 8| exhausts from the right side of piston 85 through line I20, valve I05 at the right side of piston I08 and down through pipe I45 and hand adjusted metering valve I46 to the reservoir. Valve I48 is provided to adjust the speed of retraction of piston 35, and the exhaust from the left side of piston 56 in cylinder 80 also passes through it. This exhaust rate from the left side of piston 58 is also adjustable where it passes through hand adjusted valve I41 into line I20. While the speed oi? rapid infeed and grinding infeed may be controlled by closing valves I30 and I80, the speed of retraction is unafiected by these valves which are bypassed when the main valve I05 is reversed for retraction so that retraction speed may be set as high as desired by hand operated valves I48 and I 81.

Electrical control The main solenoid operated control valve I05 is normally positioned by spring II8 to retract the wheel slide from the work. By energizing its solenoid I50, rapid and grinding "infeed are effected. This is done by moving a main operatwheel slide II to the left as collar 10 makes contact with sleeve 55. The circuit is completed from wire I58 through wires I12, I18, solenoid I1I,wire I14. switch I10 and wire I15 to wire I58. Just as collar 10 makes contact with sleeve 55, it rides over arm I88 to reopen limit switch-I10 and valve I80; At this instant collar 10 also engages arm I18 or limitswitch I80 to energize solenoid I8I and open valve I88. The circuit is completed from wires I58, I12, switch I80, wire I82, solenoid I8I, wire I84, relay operated switch I85 and wire I88 to wire I58. Relay switch I85 is normally closed, and trip switch I80 remains closed during the remainder of the grinding ini'eed cycle.

A standard electrical work sizing gage I80 is provided such as that disclosed in U. S. patent to S. A. Foster, No. 2,267,559, having double contacts which are normally open and which close successively as work size is reduced. The first contact to close has terminals I8I and I82 and is adjusted to close when work size is reduced to the point when it is desired to change from normal grinding infeed rate to slow grinding infeed rate. The second pair of contacts have terminals I93 and I84 and are adjusted to close when finished size of work is reached. As work size is reduced at normal grinding infeed speed, the first contacts with terminals I8I and I82 close to complete the circuit from wire I58 across terminals I8I and I82, relay I85, and wire I88 to wire I58. This energizes relay I85 to open switch I85. Solenoid I8I is deenergized and valve I88 closes to meter oil at slow grinding inteed rate. As finished work size is reached the second pair of contacts of gage I80 with terminals I88 and I84 close to complete the circuit across terminals I88 and I84 from wire I58 through wire I86, relay 200 and wire I64 to wire I59. This energizes relay 200, opens relay operated switch I6I to break the circuit through relay I82, thereby allowing relay operated switch I85 to open and deenergize solenoid I The main valve I05,is then reversed, grinding-infeed comes to a positive instantaneous stop and the wheel I3 is retracted from the work I4.

To operate the machine, starting with the grinding wheel in retracted position, I place a cylindrical work piece It in the headstock and rootstock and set the gage I80 to change the grinding infeed from normal to slow or finish ing switch lever I88 to the left which closes main switch contacts I88 and I51. An electric circuit is then completed across wires I58 and I58 tacts I58 and I51, relay operated switch Iti which is normally closed, through relay I82, wire I88 and through wire ltd to'iyire I58 to energize relay I62. Relay operated switch I is then closed to complete the circuit from wire I08 by way-oi wires I08 and IE1 through solenoid I50 to enersize it and through wire I58 to wire I58. When relay I82 was energized it also closed relay operated switch I80 to form a holding circuit so that when hand pressure is released on lever I55 to reopen contact I57 which is normally open, the circuit energizing solenoid I50 will nevertheless remain closed. The wheel slide II and shaft 5i now start rapidly to the left. Just before collar 10 makes contact with the end IOI of sleeve 55, it engages arm I68 of limit switch I10 to close it. This momentarily energizes solenoid "I to close valve I30 and slow the speed of movement or the grinding at the required finishedsize.

until collar 10 makes contact with the end IOI of sleeve 5'5. At that instant collar 10 actuates arm I10 to close switch I00 and open metering.

valve I30. The wheel now makes contact with the work and grinds at normal grinding infeed speed as cylinder 60 moves to the left until the gage contacts across terminals I8I and I852 close. Thisshuts down metering valve I38 so that only a small stream of oil is exhausted from cylinder 60, which continues at a slower rate to the left to allow a finish grinding infeed rate. When work size is reached, the gage contacts across terminals I83 and I84 close. Valve I05 is instantly reversed to retractthe Wheel from the work and cylinder is repositioned so that a new cycle of operationmay be started. A new work piece may then be inserted and the operation repeated. V l

The mechanism of the invention provides ex- 7 tremely smooth and finely controlled grinding infeed action since there are no couples set up along the feed shaft due to the balanced construction of the cam surfaces about the feed shaft and of the bell crank arms, which eliminates any side stresses. Since the mechanism is mounted concentrically about an extension of the standard the various objects hereinabove set forth together with many thoroughly practical advantages are successfully achieved.

As many possible embodiments may be made of the above invention and as many changes might be made in the embodiment above set forth, it is to be understood that all matter hereinbefore set forth or shown in the accompany- "ing drawings is to be interpreted as illustrative and not in a limiting sense.

I claim: 1. In a grinding machine a cross slide mounted on ways, a feed shaft connected to said cross slide, means to move said cross slide in either direction, abutment means to control final movement of said cross slide in one direction including a collar on said shaft. a sleeve slidable on said shaft to abut said collar after movement of said shaft in one direction, a piston fixedly mounted on said sleeve, 9. cylinder slidably' mounted on said piston and sleeve having cam surfaces to actuate said abutment means and fluid pressure means to actuate said cylinder.

2. In a grinding machine a cross slide mounted on ways, a feed shaft connected to said cross slide, fluid pressure means to move said cross slide in either direction and to urge it in one direction, abutment means to control finalmovement of said cross slide in one direction including a collar on said shaft, a sleeve slidable on said shaft to abut said collar after rapid movement of said shaft in one direction, a piston fixedly mounted on said sleeve, a cam actuating cylinder slidably mounted on said piston and sleeve having cam surfaces, bell crank arms abutting said sleeve and actuated by said cam surfaces and fluid pressure means to actuate said cylinder in timed relation with the movement of said cross slide.

3. In a grinding machine a cross slide mounted on ways, a feed shaft connected to said cross slide, fluid pressure means to move said cross slide rapidly to an abutment in the direction of feed to urge it against said abutment and to retract it therefrom, abutment means to control final movement of said cross slide in one direction including a collar on said shaft, a sleeve slidable on said shaft to abut said collar after rapid movement of saidcross slide in the direction of feed, a piston fixedly mounted on said sleeve, a cam actuating cylinder slidably mounted on said piston and sleeve having cam surfaces thereon, means actuated by said cam surfaces and abutting said sleeve to allow said sleeve to move in the direction of feed and to reposition it in the other direction and fluid pressure means to actuate said cylinder in timed relation with the movement of said cross slide.

4. In a grinding machine a cross slide mounted on ways, means to move said cross slide rapidly in both directions and to urge it steadily in one direction, abutment means to allow said cross slide to move very slowly in one direction including a shaftconnected to said cross slide, a collar on said shaft, a sleeve slidable on said shaft to abut said collar, a piston mounted fixedly on said sleeve, a cylinderslidable on said piston and sleeve having cam surfaces longitudinally thereof, bell crank arms actuated by said cam surfaces and abutting said sleeve, fluid pressure means to actuate said cylinder in either direction whereby movement of said cylinder in one direction allows said bell crank arms to close and allow said cross slide to move.

5. In a grinding machine a cross slide mounted on ways, fluid pressure means to move'said cross slide rapidly in either direction and to urge it steadily in one direction, abutment means to control final movement of said cross slide in one direction after rapid movement in that direction including a shaft connected to said cross slide, a

collar on said shaft and a sleeve slidably mountedon said shaft to abut said collar, bell crank arms abutting said sleeve, and cam means to rock, said bell crank arms.

6. In a grinding machine across slide mounted on ways, fluid pressure means to move said cross slide rapidly in either direction and to urge it steadily in one direction, abutment means to allow said cross slide to move slowly in one direction after rapid movement in that direction including a shaft connected to said cross slide, a collar on said shaft and a sleeveslidably mounted on said shaft to abut said collar, bell crank arms abutting said sleeve, cam means to rock said bell crank arms, fluid pressure means to actuate said cam means and means to control said fluid pressure means in timed relation with reduction of work size.

7. In a grinding machine a cross slide mounted on ways. fluid pressure means to move said cross slide rapidly in either direction and to urge it steadily in one direction, abutment means to allow said cross slide to move slowly in one direction after rapid movement in that direction including a shaft connected to said cross slide, a collar on said shaft and a sleeve slidably mounted on said shaft to abut said collar, bell crank arms abutting said sleeve, cam means to move said bell crank arms including a fluid pressure piston fixedly mounted on said sleeve, a cylinder slidable over said piston having cam surfaces, valves to control the flow of pressure in said cylinder in timed related 'with reduction of work size, solecrank arms and means momentarily to slow the.

rapid movement of said cross slide in one direction just before said collar engages said sleeve.

9. In a grinding machine a cross slide mounted on ways, means to move said cross slide rapidly in either direction and to urge it steadily in one direction, abutment means to control final movevery finely controlled final movement of said cross slide in one direction after rapid movement including a shaft connected to said cross slide, an abutting member on said shaft, a sleeve slidable on said shaft to abut said abutting member, abutting members to abut said sleeve, a fluid pressure cylinder slidable on said sleeve having cam surfaces to actuate said abutting members and valves to control the flow of fluid pressure in said cylinder in timed relation with rapid movement I of said cross slide and with reduction of work size.

11. In a grinding machine a cross slide mounted on ways, abutting means to allow a very finely actuated by said shaft to operate said solenoid. 12. In a grinding machine a cross slide mounted on ways, fluid pressure means to feed said cross slide and retract it rapidly, abutting means to allow a very finely controlled grinding infeed movement of said cross slide after rapid infeed in- 40 2,376,237

eluding a shaft connected to said cross slide, an abutting member on said shaft, asleeve slidable on said shaft to abut said abutting member, abutting members to abut said sleeve, a piston on said sleeve, a cylinder slidable on said piston and sleeve having cam surfaces to actuate said abutting members, a valve to admit fluid pressure to said fluid pressure meansand to said cylinder and to reverse the direction of flow thereof-to retract said cross slide and said cylinder. when final work size is reached.

13. In a cylindrical grinding machine a rotatable grinding wheel, a cross slide, automatic means to move said cross slide rapidly to position the wheel relative to the work for grinding, slowly at 7 various speeds for normal and slow grinding infeed and for rapidly separating the work and the wheel when finished work size is reached including a shaft connected to said cross slide, a fluid pressure cylinder, a piston in said cylinder and mounted on said shaft, an abutting member on said shaft, a sleeve on said shaft to abut said abutting member, bell crank arms to abut said sleeve, a cam to limit motion of said bell crank arms, a fluid pressure piston fixedly mounted on said sleeve and a cylinder slidable on said piston and sleeve to actuate said cam in timed relation with rapid motion of said cross slide and with reduction of work size.

, WILLIAM L. DROWN.

REFERENCES, or'rnn The following references are of record in the flle of this patent:

UNITED STATES Farmers Number Name Date 2,113,367 .Belden et a1. Apr. 5, 1938 2,267,391 Astrowski Dec. 23, 1941 Deckeret a1; May 15, 1945

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