US2680939A - Internal grinding machine - Google Patents

Description

June 15, 1954 N. s. HUMES 2,680,939

INTERNAL GRINDING MACHINE Filed May 27-. 1952 2 Sheets-Sheet l g wwwfot F a. nmwruln S 'Humt'as June 15, 1954 N. s. HUM ES 2,680,939 INTERNAL GRINDING MACHINE 'Filed May 27, 1952 2 Sheets-Sheet 2 Patented June 15, 1954 UNITED STATE E ATENT OFFICE The Heald Machine Company,

Worcester,

Mass, a corporation of Massachusetts Application May 27, 1952, Serial No. 290,155

9 Claims.

This invention relates to internal grinding machines and particularly to work sizing in connection with machines of the centerless type.

In the art of refining inner surfaces of round workpieces by the application of an internal grinding wheel or other similar finishing tool, it is usual to locate the work, that is to fix the center of the workpiece with respect to the wheel by holding one of its outer peripheral surfaces against a work support which bears a predetermined fixed spaced relation to the grinding tool.

In grinding certain types of workpieces, it is necessary to support the piece directly in line with the force exerted by the tool on the work in order to avoid deflections in the workpiece and consequent errors in sizing. The work support may be either a rotatable roll, or a fiat or concave surface, the latter conforming to the outer peripheral support surface of the workpiece and against which the workpiece is held by pressure rolls or other means while its inner surface is being refined.

Since it is the primary function of a fixed work support of the general type discussed to fix the centers of successive workpieces in the same spot with respect to the final position of the grinding tool surface, it is desirable also to arrange such a fixed work support so that appreciable variations (in terms of modern tolerances) in the outside diameters of support surfaces of successive workpieces will be compensated for with the result that the center of each workpiece will always be located at the same point with respect to the workin surface of the tool and this is the primary object of the present invention.

Essentially the invention comprises means to change the position of a fixed work support with respect to the grinding tool for each successive workpiece to the extent that the outside radius of the workpiece varies from that of the previous workpiece and in response to such variation.

In the drawings:

Fig. 1 is a partial plan view partly in section of the mechanism of the invention.

Fig. 2 is a front elevation and partly schematic view of fiuid pressure and control means for the mechanism of Fig. 1.

Fig. 3 is an end elevation view of the mechanism of Fig. 1.

Fig. 4 is an end elevation view of a modification.

Fig. 5 is a front elevation and partly schematic view of fluid pressure and control means for the mechanism of Fig. 4.

Fig. 6 is an end elevation view of some of the mechanism of Fig. 4.

Referring to Figs. 1 to 3, an internal type grinding wheel or other finishing tool H! on a spindle l i is mounted to be driven from a fixed head (not shown) to refine an inner surface l2 of a workpiece l5. The workpiece is supported, while being ground, by a fixed work support [3 having concave surfaces Eta and lab in contact with a preformed outer peripheral workpiece surface 20. The finished inside diameter of the inner surface I2 is determined in the usual manner by the position of the center of rotation of the workpiece which in turn depends upon the position of the outer workpiece surface 20 with respect to the final position of the surface of the grinding tool iii at the finish of the grinding operation. The workpiece being ground is held against the support 18 by a pair of pressure rolls 22 and 23 mounted on pivoted arms 24 and 25 which are urged together to force the rolls against the work by a spring '21. The arms 24 and 25 and also the work support l8 are carried on a resilient member which is mounted on a work head sliding table 35. A workhead 3| including a back plate 32 against which the workpiece abuts is also mounted on the table 35. The workpiece [5 may be urged against the back plate by the rolls 22 and 23 which are in a skewed position for this purpose. The workpiece is driven by the back plate 32 through a pulley 33 to which the back plate is fast.

A magazine in is arranged to feed a succession of workpieces liia, I51), I50, 85d, first to an air gage s2 and then through an offset chute as to the work support It when the work table 35 has been retracted from the grinding tool It.

An ejector mechanism indicated at has a part 46 operating to the right as viewed in Fig. 1 to push a finished workpiece l5 out of the grip between the rolls 22 and 23 and the support It and another part 4? operating also toward the right as viewed to push a workpiece [52) into the air gage 42. The workpiece l5?) in turn pushes an abutting workpiece i511 out of the air gage into the chute 44 where it rolls down into the support it ready for a successive grinding operation. The ejector part t? is fast on a rod at extending through the workhead 3| independently of the back plate 32 and its driving pulley 33 (the shaft connecting the back plate 32 and pulley as being hollow and not shown). The rod 68 is connected to an offset arm 59 on a piston rod 5%] on one end of which is mounted the ejector part 3'? and on the other of which is a piston 5: operating in a cylinder 52 toward the right as shown under fluid pressure and toward. the left under force of a spring 53.

The support member 30 being resilient, as stated, means are provided according to the invention to position the member 30 and the work support It with respect to a pre-determined position of the surface of the grinding tool it. Re ferring particularly to Fig. 3, a leaf or bow extends between the upper end 30a of the support member 38 and a base member 6| on the table 35. The central part of the bow 6G is pre loaded to the right by a spring 63 and further pressure xerted to the right against the center of the bow Gil bends the resilient support member 3i) to the right and hence moves the work support 18 away from the grinding tool "I.

Means are provided thus to move and position the work support it away from the tool Iii when a workpiece having a larger outside diameter is to be ground, and to allow the support it to be positioned closer to the tool If) for a smaller workpiece, thus fixing successive workpiece centers at the same point with respect to the tool surface. For this purpose a piston 65 and rod 66 are provided to operate in the base 5! and to abut and move against the bow 60. Air under pressure generated by a pump 10 (Fig. 1) passing through a regulating valve II, a restriction l2 and a conduit 13 is admitted to work against a diaphragm 161 and the piston 65 in a cylinder 15 in which the piston 65 operates. The amount of pressure in the line 13 determines the amount of movement to the right of the piston 65 and bow ti and hence the amount of movement of the workpiece support it away from the tool Hi. This in turn is determined by the size of a workpiece l5a in the air gage 42.

The air gage 42 has a circumferential air chamber 89 to which air is admitted from the line 13 through a branch line BI and from which air'is blown through peripheral jets 83 against the workpiece 15a being measured by the gage 2. The larger the workpiece [5a, the less air escapes through the jets 83, the greater the pressure in the line 113 and the more the work support It is moved to the right away from the tool Iii. The work support i8 is thus positioned between grinding cycles to accommodate a succeeding workpiece I521 in the gage just before the workpiece 15a is moved into the chute A i to replace the workpiece H: which has been finished.

Fluid pressure means are provided to lock the piston rod 66 and support IS in place for the next grinding operation once their position has been determined by the size of the workpiece 511 in the gage 62. For this purpose fluid under pressure in a line 85 acts against a diaphragm 86, a piston S? and a piston rod 88 forcing the latter against the piston rod 66 to hold it in a fixed position. After the piston 66 establishes the position of the work support I 8 and is locked in placed by the piston 88, fluid pressure in a line so operates the piston 5| to eject the finished workpiece i5 and to send the succeeding workpiece !Ea from the gage into the chute M. The line 99 is then exhausted, withdrawing the part 46 and allowing the workpiece 15a to roll into the support I8 ready to be ground.

Fluid under pressure is supplied by a pump 9i (Fig. 2) to a pressure line 92. An exhaust line 93 is also provided. The lines 85 and 99 are each opened successively to the pressure and exhaust lines 92 and @3 by operation of valves 95 and 96. These valves are in turned operated successively by a pivoted dog 98 on the table when the latter moves away from the wheel I!) to th lfift as seen in Fig. 2.

to the pressure line 92 and opening it to Assuming now that the parts are in position as shown in Figs. 1-3 with the valve 95 up and the fluid line opened to exhaust and the ejector piston 5| in its left position, and with the valve 96 up, opening the fluid line 85 to pressure to lock the piston 66 holding the work support It in a fixed position while the workpiece I5 is being ground and with a succeeding workpiece I541 in the gage 42, operation of the mechanism is as follows:

After the workpiece It has predetermined size, the table 35 is retracted by the usual means, i. e., moving to the left as seen in Figs. 1 and 2. The table dog 96 engages the valve 96 moving the latter down closing the line the exhaust line 93. This releases pressure on the piston rod 83 and unlocks the piston rod 56. The piston 55 and hence the work support it can now assume a position with respect to the grind ing tool H] as determined by the size of the succeeding workpiece i511 being measured in the gage 62. Further movement of the table 35 to the left releases the valve which moves up wardly again under force of its spring 9'], again opening the line 35 to pressure to lock the piston 86 in the position which has just been established. Still further movement of the table 35 to the left causes the dog 93 to depress the valve 55 momentarily opening the fluid line 90 to pressure. This operates the ejector piston 5! toward the right and back toward the left, which ejects the finished workpiece it from the support l8 and sends the new workpiece 15a down to the support 18 whose position has just been established and fixed according tothe size of the workpiece liia. At the same time a new workpiece l5b is inserted in the gage 42. Now the table 35 moves back to present the workpiece 15a to the grinding tool If], the dog as being inoperative during this return movement of the table 35. It is thus seen that the workpiece is measured and the support moved to accommodate its size before it reaches the position in which it is ground.

In a modified form of the invention shown in Figs. 4-8, a frame H6 is attached to the upper end 33a of the resilient support member 30 which carries the work support [8. Pivotally supported to swing horizontally in the frame HE is an arm H2 which carries a vertically slidable pin I I5 which is urged upwardly by a light spring H6. A spring H8 urges the swinging end of the arm H2 to the right as seen in Fig. 4 so that the pin I I5 is over the high portion of a sloping cam surface [29. A bellows 522 when actuated by air pressure in a line [23 moves the arm l [2 against the spring I I8 moving the pin I i5 toward the low portion of the cam surface :28. The pressure in the line !23 is determined by the size of a work piece I5G being measured in an airgage d2. A large diameter piece Mia increases the pressure in the line I23 causing the arm M2 to move over the low portion of the cam 129. Thereafter, fluid pressure in a line 525 expands a bellows lite until the bottom of the bellows contacts the frame llil as shown in Fig. 4. The pin 1 I5 is thereby forced downwardly against the cam surface E20, thus forcing the top 3% of the support member 39 and the workpiece support E8 to the left to a small degree, A smaller workpiece 15a in the gage 42 decreases the pressure in the line I23 allowing the pin i it to move over the higher portion of the cam surface 528 so that when the bellows itil is moved downwardly. against the frame Hi], the support 18 is forced further to the left been finished to a toward the grinding tool III. The arm H2 is, of course, positioned by the air operated bellows I22 while the pressure is off the fluid operated bellows I39. The pin H5 is, therefore, retracted'as shown in Fig. 8 and the arm is free-swinging and sensitive to slight changes of air pressure determined by the gage 22. After fluid pressure is applied against the bellows I36, the pin H5 locks the mechanism in the established position. The slope of the surface I29 is exaggerated in the drawing and is not actually enough to cause the pin H5 to slide down it when the pressure is on the pin. Air is supplied to the bellows I22 and air gage 42' from a pump Iii, through a regulating valve II, restriction l2 and the lines 8! and I23, It is controlled by a valve I32. Fluid pressure is supplied by a fluid pump 9| to a line 92'. An exhaust line 93' is provided.

In operation, when the work table 35 moves to the left as shown in Fig. 5 away from the tool III, a table cam I35 depresses the valve I32 shutting off the line I 23 but at the pressure which was established by the gage 212' when the line I23 was open to pressure. Further downward movement of the valve I32 opens the line I25 to exhaust reoperates after which upward movement of the n valve I32 under pressure of its spring I3I reopens the line I25 to fluid pressure causing downward movement of the pin I I 5 to its always same position, bending the support I8 toward the tool HI in accordance with the new position of the pin H5 on the cam surface I20.

I claim:

1. In a machine for refining an inner surface of revolution of a workpiece having an outer preformed surface of revolution and in combination a grinding tool, workpiece rotating means and support means, said support means including a support element adapted to make contact with an outside support surface of a workpiece substantially in opposition to the force applied by the tool against the work thereby to support said piece against said force during grinding, said support element being adjustably movable toward and away from the desired center of rotation of said workpiece to compensate for variations in outside diameters of said workpiece sup port surfaces in different workpieces and adjusting means to the position of said support ele ment relative to said center of rotation of a workpiece in accordance with the diameter of its said outside support surface.

2. In a machine for refining inner surfaces of revolution of workpieces having outer preformed surfaces of revolution and in combination, a rotary tool applicable to said inner workpiece surface, means to support each said workpiece from below, means to rotate each said workpiece, and a support element arranged to make contact with said outer workpiece surface substantially opposite the force applied by the tool during grinding, said support element being automatically movable toward and away from a final position of said tool to an adjusted position and means positioning said support element with espect to said final tool position in response to the diameter of the workpiece, and thereby maintaining the centers of successive workpieces at a substantially fixed distance from said final position of said tool.

3. In the combination as set forth in claim 2, means to lock said movable support element in its said adjusted position before said tool is applied to the workpiece.

4. In a machine for refining an inner surface of revolution of a workpiece, said workpiece having an outer preformed surface of revolution and in combination, a grinding tool, movable support means engaging said outer surface to fix the center of the workpiece with respect to the tool, gage means to measure the diameter of said workpiece outer surface, and means operated automatically by the gage means to locate said support means with respect to said grinding tool in accordance with said measured diameter of each said workpiece thereby compensating for variations in the diameter of each of successive workpieces.

5. In a machine for refining an inner surface of revolution of a workpiece, said workpiece having an outer preformed surface of revolution and in combination, a grinding tool, movable support means engaging said outer surface to fix the center of the workpiece with respect to the tool, gage means to measure the diameter of said outer surface, means operated automatically by the gage means to locate said support means with respect to said grinding tool in accordance with said measured diameter of each said workpiece and means to feed a succession of Workpieces to said gage means and said support means.

6. In a mach ne for refining an inner surface of revolution of a workpiece, said workpiece having an outer preformed surface of revolution and in combination, a grinding tool, movable support means to fix the center of the workpiece, gage means to measure the diameter of an outer surface of a workpiece in the gage while another is being finished by said tool, means to eject the finished workpiece and to move the workpiece in the gage into the support means and means responsive to the gage to locate the support means relative to the tool in accordance with the measured diameter of the previously measured workpiece.

7. In the combination as set forth in claim 6, a loading chute for holding a succession of workpieces, and means associated with said chute to feed a successive workpiece into said gauge as the workpiece in the gauge is moved into said support means.

8. In a machine for refining an inner surface of revolution of a workpiece, said workpiece having an outer preformed surface of revolution and in combination, a grinding tool, resiliently mounted support means, means to fix the position of said support means at a predetermined point for locating a first workpiece radially with respect to the tool during a grinding operation, gage means measuring the diameter of a succeeding workpiece while the first is being ground, means responsive to the gage means capable of moving the support means relative to the tool prior to the grinding of the said succeeding workpiece to compensate for any variation in diameter between the said workpieces and means to fix the support means in its newly established position during the grinding of a succeeding workpiece.

9. In a machine for refining an inner surface of revolution of a workpiece, said workpiece having an outer preformed surface of revolution and in combination, a retractable grinding tool, movable support means to position the workpiece radially, gage means to measure a diameter of a workpiece while another is being ground, References Cited in the file of this patent means controlled by said gage means and oper- UNITED STATES PATENTS atmg automatically in tlme with tool retraction to locate said support means and then to lock Number a Date it in position in accordance with the said meas- 5 2,080,941 Hutchmson May 1937 ured diameter thereby to compensate for any 2,109,524 Cramel' Man 1, 1938 variation in the measured diameters of succes- 2,586,987 Ortegren 1952 sive workpieces.

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