US3047987A - Apparatus for submerged grinding - Google Patents

Description

1962 w. G. BALDENHOFER ETAL 3,047,987

APPARATUS FOR SUBMERGED GRINDING Filed Jan. 25, 1961 2 Sheets-Sheet l INV EN TOR.

LLIAM G. BALDENHOFER BY FREDERICK G KRAFFT ATTORNEYS Aug- 7, 1962 w. G. BALDENHOFER ETAL 3,047,937

APPARATUS FOR SUBMERGED GRINDING Filed Jan. 23, 1961 I 2 Sheets-Sheet 2 F! (5-5 F|G 4 Fl 6'5 INVENTOR.

WILLIAM G. BALDENHOFER FREDERICK G. KRAFFT AT TOR N EYS United States Fatent @zflfirce Patented Aug. 7, 19%2 3,047,937 APPARATUS FOR SIUBMERGED GRINDING William G. Baldenhofer and Frederick G. Kraift, Springfield, Ohio, assignors to The Thompson Grinder Company, Springfield, Ohio, a corporation of Ohio Filed Jan. 23, 1961, Ser. No. 84,328

9 Claims. {CL 5192) This invention relates to an apparatus for grinding and is particularly concerned with an apparatus for effecting grinding with the workpiece and grinding wheel submerged.

In the art of machining workpieces by way of grinding with a grinding wheel, higher and higher degrees of accuracy are required and instances have occurred in which ordinary grinding techniques are lacking, with respect to producing the desired degree of accuracy economically.

Particular instances of such cases are found in connection with grinding very accurate slots in hardened workpieces, such as, for example, rotors of vane-type pumps or motors. Slots in such rotors must be held to extremely close tolerance and the ground surface must, also, have an extremely high finish.

The finish, for example, in such case should be on the order of five micro inches or better and the dimensionaccuracy is on the order of plus or minus .00002. Since such slots are ordinarily quite narrow, about .078 inch, the conventional methods of grinding, which involves the stroking of a thin grinding wheel longitudinally through the slot, has the marked disadvantage that the grinding wheel will tend to deflect and follow the surface being ground.

This not only produces inaccuracy, but causes excessive heating and excessive wear of the grinding wheel thereby greatly reducing the life of the wheel and producing parts beyond the tolerance limits, either as to size, or finish, or both. We have performed numerous experiments in dealing with this problem and have discovered that considerable improvement can be had by placing the workpiece directly under the grinding wheel and feeding the grinding wheel vertically into the slot rather than traversing the slot according to conventional practices. In this manner, the grinding wheel is caused to have the minimum amount of contact with the surface being ground and the amount of material to be removed can be divided equally between the opposite sides of the grinding wheel.

While the procedure referred to above produced marked improvement, there still existed the problem of getting suflicient coolant to the grinding wheel and workpiece to prevent the development of excessive heat with consequent distortion of the workpiece and wear of the grinding wheel.

After carrying numerous experiments, it was discovered that adequate cooling of the wheel and workpiece could be had by submerging the workpiece and wheel in coolant, rather than supplying a stream of coolant thereto, according to conventional practices.

With the foregoing in mind, it will be evident that a primary object of the present invention is the provision of an improved apparatusfor grinding workpieces, particularly, where excessive temperatures are apt to be developed, or where wheel deflection must be greatly reduced or entirely eliminated.

A still further object of this invention is the provision of an apparatus for effecting precise grinding, particularly, with a thin grinding wheel wherein the grinding wheel and workpiece operate completely submerged in coolant.

A still further object of this invention is the provision of an apparatus for operating a grinding wheel completely submerged in coolant which will eliminate the temperatures and aeration that can be created by the agitation thereof by the rotating wheel.

A still further object of this invention is the provision of an improved apparatus for grinding in winch the grind ing wheel can operate completely submerged in coolant, but by means of which apparatus the coolant is prevented from becoming aerated and thereby loosing its effectiveness.

These and other objects and advantages of the present invention will become more apparent upon reference to the following specification in which:

FIGURE 1 is an elevational view of a typical grinding machine arranged for the practice of our invention;

FlGURE 2 is a sectional view indicated by line 2--2 on FIGURE 1 and drawn at enlarged scale showing the wheel guard and the parts connected therewith in section;

FIGURE 3 is a fragmentary view similar to FIGURE 2 but drawn at still larger scale showing a workpiece being ground according to this invention;

FIGURE 4 is a view like FIGURE 3 but shows the parts of the apparatus at the conclusion of a grinding operation;

FIGURE 5 is a plan sectional view indicated by line 5-5 on FIGURE 3; and

FIGURE 6 is a sectional view indicated by line 6-6 on FIGURE 3.

Referring to the drawings somewhat more in detail, the grinding machine shown in FIGURE 1 is substantially conventional and comprises a bed it on which a table 12 is reciprocably mounted. Extending upwardly from the back of bed 10 is a column 14 that carries a slide 16 for vertical movement thereon and which slide 16 supports a wheel head that includes a drive motor con nected for driving the wheel 18 in rotation.

According to conventional practices, the machine includes controls for reciprocating the table on the bed and for controlling the vertical movement of the slide 16 on column 14 and, also, includes controls for controlling the reciprocation of the wheel head on the slide 16 whereby the wheel 18 can be positioned at any desired place over the table 12.

Referring now to FIGURE 2, it will be seen that table 12 supports a work receiving member 20 which provides means for receiving and supporting a workpiece in an accurate location. The exact construction of the work support member 20 will be determined by the type of workpiece that is being operated. The work support member may, thus, comprise a magnetic chuck or any other suitable means for fixedly holding a workpiece in a precisely located position.

According to this invention, means are provided for maintaining a body of coolant around the workpiece being ground and the wheel by which it is ground during the entire grinding operation. This means comprises a plate element 22 adapted for engaging support member 26 and for being sealed thereto as by the endless seal ring 24.

Plate 22 is attached by a flexible bellows member 26 with the wheel housing or wheel guard 28. The bellows member is preferably of a flexible plastic material or syn thetic rubber so that it will not deteriorate in the presence of the coolant. Neoprene, for example, is a suitable material.

This bellows is sealed to both the plate 22 and the wheel guard so that by admitting coolant into the wheel guard, a body of coolant can be supported therein so as to enclose and submerge the wheel and workpiece in the coolant.

The coolant is supplied to the inside of the enclosure formed between Wheel guard 28 and the bellows 26 by a conduit 30 which may have a valve 32 therein and which conduit leads to a pump 34 connected to a coolant sump 36.

FIGURES 1, 5, and 6 will show that the wheel head spams? supports two or more cylinder members 33 into which extend the double acting rams 4@ which are connected to the aforementioned plate 22. By reversibly energizing the motors that are made up of the cylinders 38 and the rams til, the plate 22. can be pressed downwardly into sealing engagement with the work support member 20, as illustrated in FIGURE 3, or elevated therefrom, as illustrated in FIGURE 4.

These motors are preferably air operated, but may consist of hydraulic or electric motors, or the movement of the plate 2% could be accomplished manually.

As will be seen particularly in FIGURE 3, 'When a workpiece 42 is put into position to be ground, the plate 22 is lowered into sealing engagement with work support member 29, and with the wheel operating, the entire enclosure or cavity defined by the wheel guard and the bellows is filled with coolant from conduit 30.

The coolant level is preferably maintained as indicated in FIGURE 3 so that the wheel is completely submerged. An air bleeder hole 44 in the wheel guard above this level permits the escape of air from the wheel guard during this filling operation, and, also, permits the escape of any air or gases released from the coolant during the grinding operation.

After the space around the workpiece and the grinding wheel has been completely filled by the coolant, the grinding operation is carried out by moving the grinding wheel and the work iece relatively vertically at the predetermined rate. As mentioned before, the workpiece is so adjusted relative to the grinding wheel that substantially equal amounts of stock are removed from the workpiece by each side of the wheel thereby substantially eliminating any tendency of the wheel to deflect and equalizing the load on opposite sides of the wheel for uniform wear thereof and for the minimum development of heat in the wheel and the workpiece.

For carrying out the method according to this invention when the wheel and workpiece are to move relatively radially of the wheel, the table 12 is locked to bed Fltand likewise the wheel head assembly is locked to slide 16 so that the only movement of the wheel and workpiece relatively during the grinding operation is radially of the wheel and in a predetermined fixed direction relative to the workpiece.

At the conclusion of the grinding operation, which occurs when the grinding wheel has reached a predetermined depth in the slot being ground, the wheel head is retracted from the workpiece, and the plate 22 is then retracted upwardly which permits the coolant to flow outwardly from beneath plate 22 to table 12 whence it is directed back to the sump 36 passing through suitable filtering means, if so desired.

It will be understood that this invention is susceptible to modification in order to adapt it to different usages and conditions; and, accordingly, it is desired to comprehend such modifications within this invention as may fall within the scope of the appended claims.

We claim:

1. In an apparatus for grinding; a workpiece support, a grinding wheel mounted for movement relative to said workpiece support, casing means carried with the wheel substantially surrounding the wheel and open on the side toward the workpiece support, means for sealingly connecting said casing means to said workpiece support, and means for supplying a body of coolant to the inside of said casing and a workpiece on said workpiece sup-port, said coolant remaining in said casing during a grinding operation by said grinding wheel, said body of coolant completely submerging at least the workpiece.

2. In an apparatus for grinding; a workpiece support, a grinding wheel movable relative to said workpiece support and having a wheel guard, means for sealingly connecting the wheel guard to the workpiece support prior to a grinding operation, and means for supplying a body of coolant to the enclosure formed by the workpiece 4 support and the wheel guard to provide for grinding of the workpiece while submerged in the coolant.

3. In an apparatus for grinding; a workpiece support, a grinding wheel movable relative to said support, a wheel guard mounted about the grinding wheel and open on the side toward the workpiece support, means for sealing the wheel guard to the workpiece support to form an enclosure in which the wheel and a workpiece on the workpiece support are located, and means for supplying coolant into the enclosure to completely submerge a workpiece on the said workpiece support and the grinding wheel during a grinding operation.

4. In an apparatus for grinding; a workpiece support, a grinding wheel movable relative to said support, a wheel guard mounted about the grinding wheel and open on the side toward the workpiece support, means for sealing the wheel guard to the workpiece support to form an enclosure in which the wheel and a workpiece on the workpiece support are located, and means for supplying coolant into the enclosure to completely submerge a workpiece on the said workpiece support and the grinding wheel during a grinding operation, said wheel guard comprising vent means in an upper portion thereof above the top of the grinding wheel.

5. In an apparatus for grinding; a workpiece support, a grinding wheel above the workpiece support, a wheel guard mounted about the grinding wheel and open toward the bottom, means carried by the wheel guard sealingly connected thereto and adapted for being moved downwardly into sealing engagement with said workpiece support to define an enclosure in which the grinding wheel and a workpiece to be ground thereby on the workpiece support are located, and means for supplying a body of coolant to said enclosure for completely submerging the grinding wheel and a workpiece on the workpiece support to be ground thereby.

6. In an apparatus for grinding; a workpiece support, a grinding wheel above the workpiece support, the grinding wheel and workpiece support being movable relatively in the vertical direction, a wheel guard mounted about the grinding wheel and open at the bottom, flexible means sealingly connected to the wheel guard adjacent the bottom thereof and adapted for being moved into sealing engagement with the workpiece support in surrounding relation to a workpiece thereon, means carried by the wheel guard for so moving the said flexible means, and means for filling the enclosure defined by the said flexible means and the workpiece support and the wheel guard with coolant.

7. In a grinding apparatus; a workpiece support, a grinding wheel positioned above the support, said support and grinding wheel being movable relatively in the vertical direction, a wheel guard mounted about the grinding wheel and open at the bottom, a fiexiblefluid tight bellows having its upper end sealingly connected with the lower part of the wheel guard, a frame sealingly connected with the lower end of the bellows, means carried by the wheel guard and attached to said frame operable for moving the frame downwardly into engagement with the workpiece support and for retracting it therefrom, seal means for sealing said frame to said workpiece support to form a fluid tight enclosure with the workpiece support and the wheel guard in which the grinding wheel and a workpiece on said support are located, and means for supplying a body of coolant to said enclosure for completely submerging said workpiece and grinding wheel.

8. In a grinding apparatus; a workpiece support, a grinding wheel positioned above the support, said support and grinding wheel being movable relatively in the vertical direction, a wheel guard mounted about the grinding wheel and open at the bottom, a flexible fluid tight bellows having its upper end sealingly connected with the lower part of the wheel guard, a frame sealingly connected with the lower end of the bellows, means carried by the wheel guard and attached to said frame operable for moving the frame downwardly into engagement with the Workpiece support and for retracting it therefrom, seal means for sealing said frame to said workpiece support to form a fluid tight enclosure with the workpiece support and the wheel guard in which the grinding wheel and a workpiece on said support are located, and means for supplying a body of coolant to said enclosure for completely submerging said workpiece and grinding wheel, said means moving said frame comprising fluid motor means connected between the wheel guard and the frame.

9. In an apparatus for grinding; a workpiece support, a grinding wheel, means for moving said grinding wheel and said workpiece support relatively, casing means carried with the wheel substantially surrounding the wheel and open on the side toward the workpiece support, means for sealingly connecting the open side of said casing means to said workpiece support along a line that forms a closed path extending completely around the region of References Cited in the file of this patent UNITED ST TES PATENTS 823,613 Miller et a1 June 19, 1906 1,093,581 Baker Apr. 14, 1914 1,969,238 Robinson Aug. 7, 1934 2,292,588 Terbrueggen Aug. 11, 1942 2,385,198 Engle Sept. 18, 1945 2,539,449 Mackman Jan. 30, 1951

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