MONTONEN JORI (FI)
| DE426819C | 1926-03-19 | |||
| US1100845A | 1914-06-23 | |||
| US3553910A | 1971-01-12 | |||
| US5265382A | 1993-11-30 |
| 1. | A cooling water circulation system for a grindstone, particularly for grinding the edge of a glass sheet, in which system the periphery or its proximity of an abrasive disc (1) mounted in a housing (3, 4; 7, 8) provided with a grinding gap (2) is subjected to the injection of cooling water, c h a r a c t e r i z e d in that the cooling water circulation loop includes one or a plurality of slit orifices (5, 6), which is adjacent to the grinding gap (2) and produces a jet of cooling water that prevents the water from escaping from the housing through the grinding gap (2) . |
| 2. | A system as set forth in claim 1, c h a r a c t e r ¬ i z e d in that the cooling water circulation loop includes two annular slit orifices (5, 6), which lie on top of each other and define therebetween an annular grinding gap (2), that the slit orifices (5, 6) are directed at an acute angle towards each other in a manner that the jets of cooling water collide with each other or with the opposite surfaces of a glass subjected to grinding in the proximity of the periphery of an abrasive disc (1). |
| 3. | A system as set forth in claim 1 or 2, c h a r a c ¬ t e r i z e d in that the slit orifice (5, 6) is an annular orifice for injecting water into the annular groove of the abrasive disc (1) over a major section of its circumference. |
| 4. | A system as set forth in claim 1 or 2, c h a r a c ¬ t e r i z e d in that the grinding gap (2) and, respectively, the slit orifices (5) defining it only extend over part of the periphery of the abrasive disc (1) and the rest of the periphery of the abrasive disc (1) is surrounded by a waterfilled housing (3, 7). |
| 5. | A system as set forth in any of claims 14, c h a r ¬ a c t e r i z e d in that the space (10, 11) defined by the housing walls (3, 4; 7, 8) is substantially filled with cooling water, such that the cooling water surrounds the abrasive disc (1). |
| 6. | A system as set forth in claim 5, c h a r a c t e r ¬ i z e d in that the housing (4, 10; 8, 11) is adapted to operate as a top separator for powdered glass by locating a top section (13) included in a water discharge duct (14) above a tapered floor (9) included in the housing, and that the discharge of the sludge of powdered glass is effected by means of a pipe (15) connected to the bottom section of the tapered floor (9). |
| 7. | A system as set forth in any of claims 16, c h a r ¬ a c t e r i z e d in that the slit orifices (5, 6) are included in the housing double jacket (3, 4; 7, 8), wherein water is delivered by means of tangential inlet pipes (12). |
| 8. | A system as set forth in any of claims 17, c h a r ¬ a c t e r i z e d in that the water jet produced by said annular slit orifices (5, 6) and the abrasive disc (1) divide the housing in two superimposed sections (10, 11). |
The present invention relates to a cooling water circulation system for a grindstone, particularly for grinding the edge of a glass sheet. The prior known systems involve a number of defects and drawbacks. The efficiency of grinding depends on that of cooling, which is not sufficient with the prior known cooling systems. A second drawback is the splashing of cooling water, the intensity of which in the prior known systems increases along with the intensity of cooling water jets applied to the periphery of an abrasive disc. Therefore, the prior known systems (US-3,553,910) require expensive and powerful exhausters in an effort to eliminate the splash¬ ing of cooling water. A third drawback in the prior known systems is the fact that the separation of powdered glass from the cooling water circulation requires special filters and water separators.
An object of the invention is to provide an improved cooling water circulation system for a grindstone, wherein the circulation and anti-splashing of cooling water can be obtained without a separate, exhauster-equipped circulation loop.
The characterizing features of the invention for ful¬ filling this object are set forth in the annexed claim 1.
By virtue of the more effective cooling achieved by the invention it is possible to enhance the grinding efficiency as well. The cooling water splashing problem will be solved at the same time. As an additional feature, it will be possible to enhance the separation of powdered glass from the cooling water circulation.
One exemplary embodiment of the invention will now be described with reference made to the accompanying drawings, in which
fig. 1 shows a cooling water circulation system of the invention in a partial vertical section and
fig. 2 shows the circulation of cooling water in the entire system.
The bottom end of a shaft 19 is fitted with an abrasive disc 1 whose periphery comes into contact with the edge of a glass sheet subjected to grinding. The abrasive disc 1 is enclosed in a housing provided by double walls 3 and 4 as well as 7 and 8. The inner walls 4 and 8 define housing spaces 10 and 11. The walls 3 and 4 are curving and converging so as to provide a slit orifice 5. Respective¬ ly, the walls 7 and 8 are curving and converging so as to provide a second slit orifice 6. In the prsent case, the slit orifices 5 and 6 are annular and extend around the entire periphery of abrasive disc 1. Between the slit orifices 5 and 6 is defined a grinding gap 2, through which the edge of a glass sheet subjected to grinding is brought into contact with the periphery of abrasive disc 1. The surfaces of walls 4 and 8 extend further beyond the slit orifices 5 and 6 to the close proximity of the surface of a glass sheet subjected to grinding. Thus, a water jet produced by annular slit orifices 5 and 6 prevents water from escaping from the housing space 10, 11. The jets even produce an ejector effect for the suction of air through the grinding gap 2 into the water- filled housing space 10, 11. The water discharges from the centre of housing space 10, 11 into a duct 13, 14. The abrasive disc 1 engulfed by water cools well since the annular orifices 5 and 6 inject water into the grinding
gap of disc 1 over the entire circumference thereof. Alternatively, the grinding gap 2 and the slit orifices 5, 6 defining it may only extend over part of the periphery of abrasive disc 1 , the rest of the periphery of abrasive disc 1 being surrounded by a water-filled housing. In practice, the grinding gap 2 and, respectively, the annular slit orifices 5, 6 should extend at least through 180° around said disc 1, so that the movements of a glass sheet subjected to grinding in the grinding gap 2 would be possible within a sufficiently wide range.
The ejector suction produced by slit orifices offers the advantage that no ex ra means is actually needed for providing the recovery of water. A cooling water pump 17 required in the circulation system in any case creates a jet, which in turn produces a suction (pressure difference). In the present case, the peripheral walls 3, 4 and 7, 8 of a protective housing are designed in such a curving shape that the jets of annular slit orifices 5, 6 are directed into a gap between these walls and collide at an acute angle with each other or with the opposite surfaces of a glass subjected to grinding. The colliding jets merge into a continuous annular jet directed towards the periphery of abrasive disc 1.
An additional benefit of the arrangement is that the water jet supports a glass in the grinding gap 2 and, thus, the glass edge is not able to contact the edge of a housing and avoids scratching. In view of increasing the supporting capacity, the upper lip of orifice 6 can be perforated, whereby the water spurting from small holes carries the glass on top of the lip the same way as a hydrostatic bearing. The suction produced by an ejector vacuums this water into the grinding gap 2, so even that does not splash around.
The housing space 10, 11 is designed to have a sufficient height, so that the vortex of cooling water driven by abrasive disc 1 serves at the same time as a centrifugal separator. The vortical action forces the powdered glass to the outer areas of housing space 11 where it continues its passage downwards and along a tapered floor 9 into a discharge pipe 15. The water discharges through a duct 13 set in the middle of housing 11 from the vortical centre, which is not easily accessible for heavier-than-water glass particles. The top end of duct 13 lies above the tapered floor 9. A duct 14 is used for carrying the water into settling tanks 16 and the water purified therein is circulated by means of a pump 17 into tangential inlet pipes 12. In the present case, the water is delivered tangentially into annular ducts between the housing walls 3, 4 and 7, 8, whereby the water flowing in the ducts is subjected to rotary motion prior to discharging out through the slit orifice 5, 6. This provides a jet discharging from orifices 5, 6 with a tangential component of speed which, when directed against a tangential splash water jet produced by the rotating disc 1 , stops the latter and no water will be splashed out. The tangential component can also be used for changing the speed of water rotating in a water cup. An inlet jet injected in the rotating direction of disc 1 increases the rotating speed of water in housing 10, 11. A high rotating speed of water in the housing improves the sludge separation capacity of the apparatus but impairs the cooling of disc 1 and makes it more difficult to retain the water in housing space 10, 11 due to a stronger centrifugal force.
A condition for the proper operation of a system of the invention is the correct design and alignment of slit orifices as well as a sufficiently powerful water jet which, on the other hand, is also the most important aim
of cooling .
It is obvious that the invention is not limited to the above described exemplary embodiment but its structural details may vary in many ways within the scope of the annexed claims. For example, the slit orifices 5, 6 can be included in separate annular ducts surrounding the protective housings.