US2301069A

US2301069A - Polishing machine

Info

Publication number: US2301069A
Application number: US306945A
Authority: US
Inventors: David E Mulholland
Original assignee: Individual
Current assignee: Individual
Priority date: 1939-11-30
Filing date: 1939-11-30
Publication date: 1942-11-03
Anticipated expiration: 1959-11-03

Description

N0 3 1942?- D. E. MuLHoLLAND 301)069 POLI sarna MACHINE Filed Nov. 30. 1939 2 Sheets-Sheet 1 Nav. 3, 1942. Q E, MULHLLAND 2,301,069l

POLISHING MACHINE Filed Nov. 30. 1939 2 Sheets-Sheet 2 m/ 7. m L L r- 2 7. 1/ Wr//Vu/ f/ 7.

Patented Nov. 3, 1942 UNITED STATESPATENT UFFICIEIv POLISHUYG MACHINE Davia E. Mul-hoiima, Reading, Pa.

Application November 30, 1939, Serial No. 306,945

6 Claims. (Cl. 51-267) This invention, generally considered, relates to metal grinding or polishing apparatus and more particularly to means associated with such apparatus for providing a coolant delivered to the Work at or adjacent its plane of contact with the Y grinding or polishing means in sufcient volume dissipated at a rate at least equal to the rate at which the said heat is generated.

Another object of the invention is to provide in connection With a grinding apparatus, including an abrading wheel or roll, means for supplying a coolant to the work operated upon by said wheel or roll so that the heat generated in the work at the plane of Contact of the abrading roll therewith will be dissipated as soon as produced Whereby a greater amount of stock can be removed from the work by a single passage of the Work in contact with the abrading roll without causing in the Work at or adjacent the line of Contact with the abrading wheel or roll any warpage or burning of the work.

A still further object of the invention is to provide, in connection with an abrading machine adapted for grinding metal sheets or the like, a plurality of coolant chambers positioned on opposite sides of the line of contact between thev 'T abrading Wheel or roll and the Work,V said chambers being adapted to serve as means for maintaining suflicient volume Vof coolant in intimate contact with the work so as to dissipate therefrom as rapidly as generated the B, t. u, caused by contact of the abrading Wheel or roll with the work.

`Still another object of the invention is to provide in connection with a machine of the type disclosed in my copending application Ser. No. 108,846, led November 2,- 1936, which eventuated in Patent No. 2,187,462, of which this application is a continuation in part, means for supplying to the sheet of metal a coolant in sucient volume, velocity and direction to prevent any warping or distortion of the sheet during its passage in contact with the abrading roll.

Other and more specific objects, residing in various features of the invention in forms, comb'inations and relationship of parts, will Vherein- 55 after appear from the description of the preferred embodiment of the invention illustrated in the accompanying drawings in which:

Figure 1 is a View in side elevation, partiallyl in section, showing the position of the chambers for supplying coolant adjacent the roll surface- Figure 2 is a top plan View showing the coolant chambers with parts of the machine removed.

Figure 3 is a side elevation of one of the coolant chambers, disclosing the means for adjusting the height of said chambers. A

Figure 4 is a perspective View illustrating in dot and dash lines theform of coolant orifices provided in the coolant chambers and the preferred form of the forward edges of the coolant chambers, showing the work sheet positionedbeneath the abrasive roll.

Figure 5 is a central cross sectional View of the parts shown in Figure 4, the work sheet being illustrated in full lines.

In the grinding of metal sheets, plates and rolls, where it is desired to remove at each pass` an appreciable amount of metal and where this grinding is carried on at a rate of speed sufficiently high to make such grinding commercial', two vital problems are encountered. The first vo1 these problems is to maintain a uniforrnabrading surface on the grinding wheel,.and `the second and more serious problem involves the prevention of injury to the surface of the work due to the heat units generated by the passage of the Work past the abrading surface of the wheel or roll,

In the past thev grinding of metal sheets has been limited to relatively narrow rolls or wheels or to the removal from the sheet of a microscopic amount of metal at each pass and prior to my invention it has been considered impossible.l to make a grinding roll of eighteen inches or more in Width and to utilize this wide grinding roll to remove from the Work a measurable amount of metal during a single pass of the work beneath the roll'.

The rst problem stated above has been successfully solved by forming the abrasive roll from a rubber bonded abrasive and by applying to the surface thereof a suiiicient volume of coolant at a sufliciently effective velocity to maintain the roll surface against destructive heat disintegration, v

The second of the problems stated above-is much more complex. As ywill hereinafter be pointed out, it is essential in the grinding of thin metal sheets, such for example as those of onetenth of an inch or less in thickness, to supply a coolant in sufficient volume and velocity as well as in the proper direction at or adjacent the plane of contact of the sheet with the abrasive roll so as to dissipate the heat units as the same are generated since unless this is done the friction between the roll and sheet causes a buckling and burning of the sheet at the plane of contact of the sheet and abrading roll. The thinness of the metal sheet prevents the heat from being conducted away from the point or plane or contact at as fast a rate as the sheet is moved beneath the abrasive roll. Hence the thin sheet will buckle and distort on both sides of the plane of contact and in this Way render useless the grinding of the sheet which is to provide thereon a uniform flat surface.

In the grinding of thick metal sheets, dies and the like there is suiiicient metal adjacent the area in contact with the abraoling roll or sheet to prevent the buckling of the plate and this is likewise true where the work is a roll rather than a fiat plate or sheet. While warpage does not occur in the absenceof a coolant used in sufficient volume, velocity and direction in connection with plate or roll grinding, the heat which is generated causes the surface surrounding the plane of contact to expand. This eXpansion of the metal at the line of contact increases the pressure of grinding, which consequently increases the heat units which are generated and therefore sets up greater expansion. Consequently there is a tendency to grind unevenly and moreover the expansion of the limited areas, as described above, produces a series of hairline cracks or heat checks which are extremely detrimental to the finished surface.

It is well known that when water is in contact with a metal surface and the water is caused to move a thin film of the water which is in intimate contact with the metal surface will not partake of the movement of the main body of the water. If we consider that water is composed of a series of very thin films of indenite thickness and each roughly paralleling the surface, the movement of the layer of water can be illustrated by the movement of a plurality of stacked cards, each sliding over the adjacent card but the movement of the lrn immediately above the film which is in contact with the sheet will be less than the movement of the next superimposed iilrri and the same will be true of each succeeding film, that is to say the farther the film is removed from the one in contact with the metal surface the greater will be the movement and the less will be the effort required to move the same. The rate of transfer of the heat units from the metal surface to the water is greatly impeded by the adherence of the film adjacent the metal sheet.

It is therefore essential, if water or other coolant is to be effectively applied, that the means of application shall first provide a sufficient film sorption by the successive filaments of the heat units generated in the plate immediately below the same.Y Velocity is of no value unless there is obtained by such velocity the breaking up of these adhering filaments and this canbe obtained by causing the nozzle or jet to be inclined to the longitudinal axis of the roll so as to cause the successive nozzles to induce an exceedingly rapid iiow of the coolant substantially parallel to the axis of the roll.

I have found that when the velocity of the disturbing fluid, that is each jet, reaches that value induced by a pressure per square inch on the jet of approximately two hundred and fifty (250) pounds per square inch and where such a jet is passing through a nozzle whose diameter is one thirty-second (3%) of an inch and where, as stated above, the nozzles are so positioned and in such number as to provide a series of overlapping arcs of effective area inducing a flow of the coolant fluid parallel or substantially parallel to the axis of the roll, there can be removed .O01 of stock from a steel sheet .010 in thickness and at a rate of eight (8) feet per minute without any disturbance to or injury of the iinished surface of the sheet. v

From the remarks previously made it will, it is believed, be obvious that it is essential, in order to effectively cool a relatively thin sheet during the grinding thereof, and .by relatively thin is, of course, meant plates of a few hundredths of an inch in thickness, that is a tenth of an inch or less, to break up and dissipate the initial film and the subsequent films formed on the surface of the plate immediately adjacent the contact plane between the plate and therabrasive roll and in order to accomplish this result it is essential to use high velocity in connection with the cooling medium or' coolant. High velocity alone, however, will not result in the disruption of the film. It is, therefore, essential to provide means whereby the lilm is not only broken up or dissipated but a constant and continued flow of fresh coolant is delivered to the entire surface of the plate at points closely adjacent the line of contact between the plate and the roll.

We have all observed the series of sparks generated by applying a grinding wheel to a steel or iron plate. It was and is generally believed that by immersing the plate in what might be termed a static coolant that no sparks would be' gen,- erated by the contact of the roll surface with the plate. Such is not the case, however, as I have found by experimentation that even when the plate is immersed in liquid a series of sparks is projected and while these sparks are of short duration they, nevertheless, are visible and produce a decided glow in the coolant immediately in the rear of the line of contact between the sheet and roll and the greater the depth of cut the greater the volume of sparks and the resultant glow in the adjacent coolant.

There is one other aspect of thebroad principle which should be touched upon. Prior to the use of abrasive grits bonded in rubber as disclosed Vin my Patent No. 2,106,186, and my application Ser. No. 108,846, the general procedure in the grinding of steel plates was to use abrasive grains bonded in glue and secured to cloth disks maintained in roll form by guide or pressure plates applied at opposite ends of the abrasive material, or abrasive grains bonded to the surface of cloth or paper belts. l

With such mechanism no coolant could be used since glue, being hydroscopic, would immediately soften in the presence of a coolant and would permit the abrasive grain to loosen and be thrown off of the roll. Consequently it Arequired numerous passes of the plate beneath the abrasive roll to remove from such plate an amount of material which I can now remove in a single pass of the plate beneath the roll. If, however, an attempt is made to grind with a rubber bonded abrasive roll without the use of a coolant the temperature of the roll rises with great rapidity, the rubber is softened and the grits being no longer held are no longer of value in forming a uniform grinding surface so that a supplyof coolant is essential not only to maintain the plate in condition to prevent its distortion, cracking and curving and a coolant is also essential to preserve the surface of the abrasive wheel or roll since a sudden heating of the periphery of such an abrasive wheel or roll would cause strains that might result in wheel rupture and this effect would be present even though other organic bonds or vitreous or ceramic bonds were used to hold the abrasive grains.

Referring now to the disclosure of the drawings in detail, I have illustrated in Figure 1 a fragmentary section of the polishing machine illustrated in my co-pending application Ser. No. 108,846 and in this fragmentary section there is indicated by the reference character I an abrasive roll having an outer and an inner surface 2, and the said roll is mounted on a shaft 3 journaled in bearings carried by the main frame 4 of the machine. Beneath the abrasive roll are the supporting rolls carried on a pivoted carriage 6, the supporting roll being positively driven by the shaft 1, the worm of which engages the pinion 8 fastened to the shaft of the roll 5. Supported on the pivoted carriage are the guides 9 and I0 upon which the plate to be polished is adapted to lie, and supported immediately above the guides 9 and I0 are the chambers II for supplying coolant to portions of the work immediately adjacent the portion thereof in contact with the polishing roll. Each of the coolant supplying chambers, which may be advantageously formed of cast metal, progressively decreases in height toward its discharge end, so that the latter may be disposed near the point of contact between the work and the polishing roll and thus cause the coolant to discharge directly onto portions of the work immediately adjacent the portion in contact with the polishing roll. In the rear of each chamber II is formed a compartment I2 having a removable back plate I3 provided with means I 4 through which coolant is supplied to the compartment. Communicating with the compartment I2 and extending forwardly therefrom are a plurality of ducts I3, the discharge ends of which are disposed as indicated at I6 so as to cause the coolant to issue therefrom at an oblique angle to the direction of travel of the work. By causing the coolant to discharge onto the work in this manner under a pressure preferably in excess of two hundred and fifty` (250) pounds per square inch, the coolant will ow transversely of the work at a velocity which will effect such eflicient results that the polishing wheel may remove a greater amount of stock per pass than has heretofore been considered possible.

Each of the coolant supplying chambers is vertically movable Within guides I1 formed on the inner sides of the side Walls 24 of the main frame of the polishing unit, so that, as the polishing wheel wears, they may be easily adjusted. The mechanism for effecting vertical adjustment of each of the chambers may advantageously consist of a transversely extending shaft I8 which is provided with bevel gears I9 for respectively cooperating with similar gear mounted on the lower ends of vertically disposed shaft 2| which are respectively screw-threaded at theirupper ends for cooperating with the end portions of the chamber. The horizontal shaft I8 may be conveniently journaled in the brackets 22 rigid with the side walls of the frame 24 and at one end it extends through the adjacent side wall of the frame where it is provided with a hand wheel 23. The polishing wheel is preferably enclosed by a sheet metal hood within which f is mounted means for freeing the periphery of the .polishing roll of particles of grit and other waste material which may adhere thereto.

The forward edge of the coolant supply chamber, that is the portion extending beneath the polishing roll, is preferably formed as shown in perspective in Figure 4 and in cross section in Figure 5. Since these coolant supply chambers are identical a description of one will suflice for both. This projecting portion is preferably Wedge shaped, having a lower beveled surface 25 and an upper beveled surface 26. The surface 26 underlies the periphery of the abrasive roll I, while the surface 25 is spaced from the adjacent surface of the portionB of the metal plate being ground or polished. At the rear of the surface 2B I preferably provide a vertical or substantially vertical lip 21 followed by a horizontal portion terminating in the vertical lip 28. On the underside at the end of the portion 25 I provide a substantially horizontal portion 29 and another portion 30 also substantially horizontal but spaced at a greater distance from the upper surface ofthe plate than is the surface 29. It will be understood, particularly from the illustration in Figure 4, that the orifices I6 terminate beneath the edge of the surface 25 and there is, therefore, formed between the underside of the abrasive roll I and the underside of the surfaces 25 of each of the coolant supply chambers a pocket or recess in which the coolant is maintained during the movement of the plate. The chamber prevents the dissipation of the coolant except along the lines of least resistance, namely substantially parallel to the axis of the abrasive roll, which action is of course aided by the direction of the respective orifices I6.

Various modifications and changes in the details of construction of the specific embodiment of the invention described and illustrated herein may, of course, be made without departing from the spirit of the invention as defined by the appended claims.

Having thus described my invention, what I claim is:

1. An abrading machine including an abrading roll, a work supporting roll positioned beneath and extending parallel with said abrading roll and adapted to support a sheet in contact with said abrading roll, means disposed above the area of contact of said abrading roll with the sheet comprising a hollow chamber having a plurality of spaced nozzles housed therein for supplying substantially adjacent to said area a contact of coolant, and means for supplying to said chamber a sufficient volume of coolant to cause the coolant discharged from said chamber to have sufficient velocity to substantially dissipate the B. t. u. generated in the adjacent portion of said sheet by the operation of said abrading roll.

2. An abrading machine including a driven abrading roll, a driven work supporting roll positioned beneath and extending parallel to the said abrading roll and adapted to support a sheet in contact with said abrading roll, coolant supply chambers disposed above the area of contact of said abrading roll and sheet and on opposite sides of the longitudinal axis of said abrading roll, means for supplying coolant under pressure to said chambers, and means associated with each chamber comprising a plurality of connected nozzles each disposed at an angle to the direction of movement of said sheet and at an angle to the axis of the said abrading roll, said nozzles being so positioned and arranged as to discharge the said coolant in an amount and under sufficient velocity to substantially dissipate the B. t. u. generated in the sheet at and-adjacent the plane of contact of said sheet with said roll.

3. An abrading machine including a roll having a continuous abrading surface, a pivotally mounted work supporting roll positioned beneath said abrading roll, a coolant chamber positioned above a horizontal plane tangent to the lowermost surface of the abrading roll, a portion of said chamber extending toward and closely adjacent the surface of said last named roll, a plurality of nozzles housed within said chamber, each of said nozzles being positioned to project a coolant from said chamber toward the lowermost portion of said abrading roll and at an angle of less than ninety degrees to the axis thereof, and means for supplying coolant under pressure to said chamber.

4. Anabrading machine including a roll having a continuous abrading surface, a pivotally mounted Work supporting roll positioned beneath said abrading roll, a plurality of coolant chambers each positioned above a `horizontal plane tangent to the lowermost surface of the abrading roll and on opposite sides of the vaxis thereof, a portion of each of said chambers extending to a point adjacent the surface of said roll, a plurality of nozzles housed within each chamber, each of said nozzles being positioned to project a coolant from the adjacent chamber toward the lowermost surface of said abrading roll, and means for supplying coolant lunder pressure to said chambers.

5. An abrading machine `including a driven roll having an abrading surface and a driven pivotally mounted work supporting roll positioned beneath the first named roll, coolant means including a plurality of connected nozzles adapted to supply coolant to said abrading roll and to a sheet supported in contact therewith by the work supporting roll, each of said nozzles being adapted to direct a supply of coolant to said abrading roll and to a sheet supported in contact therewith by the work supporting roll, each of said nozzles being adapted to direct a supply of coolant toward the area of contact between said abrading roll and said sheet, each of said nozzles extending in a substantially horizontal plane and at an angle of less than ninety degrees to the axis of said abrading roll, means for supplying coolant to said nozzles under pressure, said means for connecting the said nozzles being adapted to overlie and contact the discharged coolant, said last named means and the angular direction of said nozzles causing the surplus coolant to flow substantially parallel to the longitudinal axis of said abrading roll.

6. An abrading machine including a driven roll having an abrading surface, a work supporting rollI positioned beneath the same, the latter being both pivotally and adjustably mounted, coolant means including a plurality of connected nozzles adapted to supply coolant to said abrading roll and to a sheet in Contact therewith at a plurality of points adjacent the planeV of contact between said sheet and roll, and means for connecting said nozzles, said means overlying the adjacent portion of said sheet and positioned closely adjacent the periphery :of said abrading roll, each of said nozzles extending in substantially a horizontal plane but at an angle to the direction of movement of said sheet, said connecting means cooperating with the said nozzles to cause the surplus coolant to flow in a predetermined path, and means for supplying coolant at a uniform pressure to each of said nozzles.

DAVID E. MULHOLLAND.