US2364418A - Coolant circulating system - Google Patents

Description

I Dec. 5, 1944. P. F. BARKER- I COOLANT CIRCULATING SYSTEM Filed Aug. 3, 1942 2 Sheets-Sheet 1 PAUL BARKER 8g W H We Dec. 5, 1944. P. F. BARKER 2,364,418

COOLANT CIRCULATING SYSTEM Fi'lpd Aug. 5, 1942 2 Sheets-Sheet 2 Q 5 Q Emaentor PHI/L F. BARKER Gttomeg are difficult to Patented Dec. 5, 1944 COOLAN T CIRCULATIN G SYSTEM Paul F. Barker, Brighton,

Gleason Works, Rochester,

of New York N. Y., assignor to N. Y., a corporation Application August 3, 1942, Serial No. 453,366

2 Claims.

The present invention relates to grinding machines and more particularly to the coolant-circulating systems of such machines.

In most grinding, especially in most gear grinding, it is the practice today to wet-grind, that is, to supply a liquid coolant to the grinding wheel and work at their area of contact in order to cool the wheel and the work and to wash away the bits of metal, which are ground off the work, and the abrasive grits, that are WOI'n off of the wheel, in the grinding operation. The coolant is usually pumped onto the wheel and work from a sump or tank mounted in the base of the grinding machine, and after use the coolant flows back to the sump for use again. Since the returning liquid is laden with particles of metal and 'abra- I sive, it is necessary to clean the coolant before it is used again, otherwise the bits of metal and abrasive will be pumped up onto the Work again and may become wedged between the wheel and work, causing scratching of the Work and rapid wear of the wheel.

Water or a suitable emulsion may beusedas the coolant, but in recent years it has become more and more the practice to use oil for this purpose. Where water is employed as the coolant, it is usual to provide the sump or tank with two chambers, a settling chamber and a pump chamber, constructed in such way that the coolant will have tooverflow from the settling chamher into the pump chamber. The settling chamber is made large enough to allow the particles of metal and abrasive to settle out of the coolant liquid into the bottom of the chamber. In some cases, also, a system of bafiles is employed which the coolant has to return to the pump chamber. These aid in the removal of the abrasivegrits and metal particles from the coolant.

Where oil is used as a coolant, however, it has been found that neither the settling chamber, nor the baffle system, nor the two combined ,operate very satisfactorily. Because of the viscosity of the oil, the particles tend to remain in suspension and the finer particles especially do not settle out but are carried over into the pump chamber where they are returned suspended in the coolant to the wheel and the work. It has become the practice, therefore, to filter the cooling oil before using it again. The ordinary commercial filters are, however, expensive, and they clean. Moreover, they have to be cleaned quite often because under the conditions encountered in a grinding operation, they load up quickly.

The primary object of the present invention is through able conduits to to provide a coolant-circulating system, especially for use where oil is employed as the cooling medium, which will insure delivery of clean coolant to the wheel and the work.

Another object of the invention is to provide a filter unit for use in a coolant-circulating system that will be efficient, simple, and inexpensive, and, moreover, that will be easy and cheap to service.

Other objects of the invention will be apparent hereinafter from the specification and ,from the recital of the appended claims.

In the drawings:

Fig. 1 is the Slide elevation of a standard form of spiral bevel and hypoid pinion grinder on which the coolant-circulating system and filter unit of the present invention is employed;

Fig. 2 is a plan view of the principal parts of the coolant-circulating system, including the filter unit; and

Fig. 3 is a transverse sectional view through these parts.

In the coolant-circulating system of the present invention, the coolant is pumped from the sump through a filter unit and thence through suitthe wheel and work, and after use, the coolant flows back into the sump whence it is pumped again through the system. The filte-r unit consists simply of a pail partially filled' With small rhomboidal or lozenge-shaped cast iron pieces or with crushed stone. As the coolant is pumped through the filter unit, the chips and abrasive grits are caught and removed. The use of crushed stone as the filtering medium is preferred. In fact, the discovery that such a material may be employed as a filtering medium in the coolant-circulating system of a grinding machine is one of the features of the present invention, Crushed stone can be obtained readily almost anywhere and it is so cheap that it can be thrown away. after use. Cast iron pieces .On the other hand are are impractical to clean. Moreover, if the quantity of stone used warrants it, the stone can be cleaned in an incinerator without damage, whereas the heat required to burn 01f the chips and grits would melt or fuse cast iron pieces.

While the invention may be applied to any type of grinding machine, it is shown in the drawings in use on a spiral bevel and hypoid pinion grinder of the type illustrated in the patent of Ernest Wildhaber, No. 2,252,743, of August 19, 1941. Grinding ,on this machine is effected by a rotary annular grinding wheel, such as designated at W in Fig. 1, and the Work piece is a spiral bevel more expensive, and they or hypoid pinion, such as denoted at P in Fig. 1, the side surfaces of whose teeth are to be ground by the wheel. A suitable guard I is provided to enclose the wheel, and coolant is supplied to the wheel and work at the area of their engagement through a nozzle 1 l which is suitably mounted in the guard H). The coolant is pumped to the nozzle H from a tank, which is designated as a whole at [2, and which is removably mounted in the base l4 of the machine.

The tank is divided into two chambers. One of these chambers, which is denoted at l5, contains the filter unit. It is square shaped and is formed in one corner of the tank. It is separated from the other chamber, which is denoted at [6, by the partition walls l1 and 18. The chamber I6 is L-shaped and forms the sump chamber proper. The coolant falling from the guard I0, and draining back to the tank, after use, flows into the sump chamber l6 through the rectangular opening in the top wall of this chamber. The used coolant is conducted to the sump opening 20 through a suitable conduit (not shown) which may be in the form of piping, or a drain trough, or the like.

The filter unit is mounted in the chamber I5. The filter unit comprises a pail which has apertures 26 in its bottom and which is partially filled with crushed stone or with metal pieces 21. The pail is flanged at its top and depends through a circular opening formed in the top wall 28 of the chamber 15. The flanged rim of the pail seats on the surrounding part of the top wall 28 of the chamber l5 and the pail is thus suspended in the chamber.

The opening in the top wall 28 is closed by a cover plate 30 which is hinged on the top wall 28 by means of the hinge pin 3|. The cover plate may be clamped down to seal it against leakage by a clamping bar 32 and a clamping screw 33. The clamp bar is pivoted at one end on a pin 34 which is mounted in the plate 28 and at its opposite end it is notched to engage under the head of a pin 35 which is also secured in the plate 28. A bail 36 is provided for the pail so that it can be lifted out of the chamber l5 to clean or remove the stones 21.

The coolant is pumped from the sump chamber l6 by a pump of any suitable construction such as a centrifugal pump shown at 40 in the drawings. The coolant is drawn into the pump through the duct 4!. From the pump 40, the coolant is pumped through the piping 42 into a duct 43 that may be formed by an angular piece of sheet metal which is secured to the side wall l1 and top wall 28 of the chamber 15. The duct 43 communicates through an opening 44 in the top wall 28 with a duct 45 that is formed in the cover plate 30. This duct 45 conveys the oil to the pail 25, and the pump pressure forces the oil through the filter pieces 21 into the chamber l5 from whence the pressure forces it into the pipe 41. This pipe is secured in an opening in the top wall 28 of the chamber l5. There are two pipes 48 and 49, respectively, connected to the pipe 41. The pipe 48 communicates with the nozzle II and supplies the coolant to the area of contact of the wheel and the work. The pipe 49 is an overflow pipe and preferably conducts coolant to the drain trough or piping through which the coolant returns to the sump chamber after use. The coolant flowing through the pipe 48 helps wash the grit and chips down into the sump and keep the. trough or'conduit clean.

There is a hand operated valve 5| mounted in the pipe 41 to control the flow of liquid between the pipe 41 and the pipe 49. The pump pressure is greater than that required to force the necessary quantity of coolant to the area of engagement of the wheel and the work, and the excess liquid flows through the pipe 49 to the sump. Through continued use, the stones 21 pick up more and more chips and grits and the interstices between the stones become gradually clogged up so that more and more pressure is required to force the dirty oil through these filter pieces. Thus the amount of pressure for carrying the coolant to the point of operation gradually decreases with use of a given charge of the filter unit, so that it is necessary for the operator from time to time to adjust the valve 5| to decrease the flow between the pipes 41 and 49 and thereby keep up the necessary pressure in the pipe 48. This is the purpose of the valve 5!.

When the filter unit becomes so clogged that it is no longer usable, a pail 25 can be removed from the chamber [5 by opening the cover plate 30, and a new pail with clean stones can be put in its place. The top wall 53 of the sump chamber I6 is provided with a cleanout opening which is closed by a hinged cover plate 54. Beneath this cover plate is a circular drain-plate 55. This drain plate has holes in it and is supported by the top-wall of the chamber IS. The cover plate 54 is shown closed in Fig. 2. When a filter unit is removed from the chamber [5, the coverplate 54 may be raised and the pail can then be placed on the top of the drain plate, as is the pail 25 in Fig. 3. so that the oil remaining in the pail can drain into the sump and not be wasted.

As already indicated, the filter pieces 21 may be of any suitable material, but are preferably crushed stone. The stones used may be of /4" to screening.

It will be noted that in the coolant-circulating system described, the filter unit is onthe pressure side of the system. This makes for extendedlife of a charge of the filter unit, because the pump pressure will force the coolant through the filter when a mere gravity feed would clog. Thus if the filter unit were so positioned as to filter the dirty oil flowing back to the sump by gravity from the wheel and work, the useful life of a given charge of stones would be relatively short for there would not be sufiicient pressure to force the dirty oil through the stones after they began to load up with chips and grit.

While the invention has been described in connection with a particular embodiment thereof and a particular use therefor, it will be understood that it is capable of further modification and use. This application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice in the art to which the invention pertains and as may be applied to the essential features hereinbefore set forth and as fall within the scope of the invention or the limits of the appended claims.

Having thus described my invention, what I claim is:

1. In agrinding machine having a work suport and a grinding wheel, a system for circulating coolant to the point of engagement of the wheel with the work comprising an enclosed prising an enclosed sump chamber sump, an enclosed filter chamber, an enclosed filter unit in the form of a pail removably mounted in the filter chamber and having openings in one wall thereof which communicate with the filter chamber so that the coolant may flow from said unit into the chamber, said filter unit being of such dimension as to occupy only part of the filter chamber, a pump for pumping coolant out of the sump and through the filter unti into the filter chamber, and piping for conducting the coolant from the filter chamber to the point of engagement of the wheel with the work, and means for conducting the used coolant back to the sump for recirculation by the pump.

2. A coolant circulating system for a grinding machine, particularly for a machine employing oil of relatively high viscosity as a coolant, comfor the coolant, a fully enclosed filter chamber separated from the sump chamber, a filter unit removably mounted in the filter chamber and comprising a pail partially filled with irregular shaped insoluble pieces and having openings in its bottom for passage of the coolant therethrough, a pump for pumping the coolant from the sump chamber into the top of said pail, piping for conducting the coolant from the filter chamber to the point of use after the coolant has passed through the filter unit, and means for conducting the coolant after use directly back to the sump chamber, said enclosed sump chamber having drainage openings in its top wall over which a filter pail may be placed, when removed from the filter chamber, to permit drainage back into the sump of the coolant remaining in said pail.

. PAUL F. BARKER.

Images