Polishing Machine

Abstract

A polishing machine load plate unit to which workpieces are affixed for polishing, and through which fluid is directed for effecting cooling of the unit.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a polishing machine comprised of a rotatable polishing wheel assembly, and means for urging work pieces to be polished into engagement with the upper surface of the polishing wheel assembly.

2. Description of the Prior Art

One type of polishing machine, as disclosed in the copending application of Stephen A. Boettcher, Ser. No. 659,780, filed Aug. 10, 1967, comprises a horizontal rotatable backing wheel, a polishing cloth extending across the upper surface of the backing wheel, a load plate unit adapted to have work pieces affixed to the lower surface thereof and to be positioned over the backing wheel with the workpieces engaging the polishing cloth, and means, including a vertical spindle assembly, for centering and applying pressure to the load plate unit In this machine, the load plate unit is a unitary plate, and heat generated therein during the polishing operation is dissipated solely into the ambient air.

SUMMARY OF THE INVENTION

In accordance with the present invention, the load plate unit is provided with an inlet for receiving fluid, and with passageway means communicating with the inlet and opening outwardly of the unit to accommodate discharge of fluid from the inlet through the unit for effecting cooling thereof. Additionally, the spindle assembly is provided with fluid transmission means for receiving fluid and transmitting the same to the inlet. In this manner, the load plate unit is refrigerated to compensate for heat developed therein during the polishing operation.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevational view, with portions being broken away and shown in section, of a polishing machine incorporating the principles of the present invention;

FIG. 2 is a horizontal view, taken substantially along the line 2--2 in FIG. 1, looking in the direction indicated by the arrows; and

FIG. 3 is a vertical median sectional view, on an enlarged scale, of the load plate unit and spindle assembly of the present invention, and of other machine components associated therewith.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to FIG. 1, there is indicated generally by the reference numeral 10 a polishing machine incorporating the principles of the present invention. The polishing machine 10 comprises framework including a substantially cylindrical housing 12 supported by a base ring 14. Suitably secured to the opposite sides of the housing 12 are the lower ends of vertical columns 16. Extending between the upper ends of the columns 16 is a horizontal bridge member 18 provided with opposed pairs of lateral arms 20. Mounted at the outer end of each of the four arms 20 is a vertical pneumatic piston and cylinder assembly 22 which includes a cylinder 24, a stabilizer sleeve 25 and a piston rod 26.

A cylindrical collar 28 is mounted at the upper end of the housing 12 by means of an annular inclined wall 30. Also mounted in the housing 12 is a main drive motor 32 operatively connected to a conventional speed reducer unit 34 supported in the collar 28. The output shaft of the speed reducer 34, in a known manner, is connected to, and serves to effect rotation of, a generally horizontal polishing wheel assembly 36 shown in FIGS. 2 and 3.

The polishing wheel assembly 36 is comprised of an annular backing wheel 38 and a polishing cloth 40 extending across the upper face thereof. The backing wheel 38 is preferably formed of a metal, such as brass, having a high heat conductivity. The polishing cloth 40, which may for example be either sail cloth or a synthetic nonwoven cloth, is retained in position by means of a ring or hoop member 42 suitably clamped about the outer periphery of the backing wheel 38. In place of cloth, a felt material may be either clamped to the backing wheel 38 or glued thereon.

A freely flowing polishing slurry is adapted to be fed to the polishing wheel assembly 36 by a tube or spout 44 extending downwardly from the bridge member 18 as shown in FIG. 1. The slurry is delivered to the spout 44 through tubing 46 connected to a sump pump unit 48 located in the lower portion of the housing 12. The polishing slurry flowing from the polishing wheel assembly 36 is collected by the inclined wall 30, which serves as a drip pan, and is directed to a drain. The polishing slurry may, by way of example, comprise a polishing compound--such as one having an abrasive base of iron oxide, cerium oxide or zirconium oxide--suspended or mixed in water.

Secured in the lower end of each of the piston rods 26 is a vertical spindle assembly 50. Each spindle assembly 50, as shown in FIG. 3, comprises a spindle 52 and a central axial tube 54 secured therein, with an annular clearance 55 surrounding a substantial portion of the tube. The spindle 52 is formed with an opening 56 which is aligned with the interior opening 58 of the tube 54 and therewith defines a central axial opening in the spindle assembly 50. The spindle 52 is also formed with a radial opening 60 which communicates with the spindle opening 56 and with the annular groove 62 of a revolvable collar member 64. An aperture 66, which is formed in the collar member 64 and communicates with the annular groove 62, is adapted to be connected to a source of fluid under pressure. The spindle openings 56 and 60 and the tube opening 58 define fluid transmission means for a purpose to be presently described.

Connected to the lower end of each of the spindles 52, as shown in FIG. 3, is a generally horizontal circular pressure disc 68 having engagement means in the form of an annular ridge 70 at the lower surface thereof. Provided between the spindle 52 and the pressure disc 68 is a floating connection in the form of a universal ball bearing assembly 72 which is maintained in position by a retaining plate 74 secured to the pressure disc 68. Suitably secured to the spindle 52 immediately above the retaining plate 74 is a collar 76 which serves to shield the bearing assembly 72 from polishing mixture and other foreign material.

Associated with each pressure disc 68 is a generally horizontal circular load plate unit 78 which, as shown in FIG. 3, is comprised of upper and lower plate sections 80 and 82. The plate sections 80 and 82 are secured together by means of a plurality of bolts 84, and are maintained in spaced apart relating by means of washers 86 interposed between the plates about the bolts 84. The space maintained between the plate sections 80 and 82 serves to define radial passageway means for a purpose to be described hereinafter. In addition, the lower plate section 82 is formed with a central pocket 88, and the upper plate section 80 is formed with a central axial inlet opening 90 in which is mounted an O-ring 91. The pocket 88 and the opening 90 together define a cavity for receiving fluid under pressure. The upper surface of the upper plate section 80 is provided with engagement means in the form of an annular recess 92 which is adapted to receive the annular ridge 70 of the pressure disc 68, while the lower surface of the lower plate section 82 is adapted to have affixed thereto workpieces 94. Finally, the polishing wheel assembly 36 is surrounded by an annular thin-walled shroud 96 in a manner and for a purpose described in the aforesaid copending application of Stephen A. Boettcher.

In preparation for polishing, the pneumatic assemblies 22 are suitable actuated to retract the piston rods 26 and the spindle assemblies 50 upwardly. At a location remote from the machine 10, workpieces 94 to be polished are affixed, for example by paraffin, in a known manner to the lower surface of the load plate units 78. The load plate units 78 and work pieces 94 affixed thereto are then moved onto the polishing wheel assembly 36 and positioned beneath the respective pressure discs 68, The pneumatic assemblies 22 are actuated to distend the piston rods 26 and the spindle assemblies 50 downwardly until the ridges 70 of the pressure discs 68 are engaged under the desired pressure in the recesses 92 of the load plate units 78. At the same time, the lower tube section of each spindle assembly is received in the axial inlet opening 90 in the associated upper plate section 80, with the O-ring 91 serving as a rotary pressure seal.

Next, the polishing wheel assembly 36 is rotated and polishing material is delivered from the spout 44 to the surface thereof. Also, fluid--preferably a gas such as air--is admitted under pressure into the annular groove 62 of the collar member 64, and is transmitted by the spindle openings 60 and 56 and the tube opening 58 to the inlet 90 in the load plate unit 78. From the inlet, the gas is discharged radially between the plate sections 80 and 82. As the gas is thus discharged, a gradual pressure drop, and an expansion, of the gas occur, with a corresponding reduction in temperature, which effects cooling of the load plate unit 78 to offset the heat developed therein during the polishing operation. The cooling effect can result from convection as well as pressure drop. However, to obtain maximum cooling effect, the system should be designed such that a pressure drop occurs within the load plate unit 78 or as close thereto as possible. The spindles 52 and pressure discs 68 serve to center the work plate units 78, and the universal connections between the spindles 52 and pressure discs 68 accommodate floating of the load plate units 78, as work pieces are being polished. Also, the annular clearance 55 surrounding each tube 54 permits the latter to flex during swivel movement of the associated pressure disc and load plate unit.

Because of the occurrence of moisture in the described cooling system, the tube 54 and the upper and lower plate sections 80 and 82 are preferably fabricated of stainless steel. Also, to avoid clogging in the gap between the plate sections 80 and 82, a filter or other entrapment means (not shown) may be mounted in the central cavity of the load plate unit 78. Additionally, since the lower plate section 82 alone requires cooling, it is preferable that the upper plate section 80 be insulated in any conventional manner (not shown). Further, to obtain temperature modulation, the compressed gas is preferably introduced to the cooling system through a manually variable pressure regulator (not shown). Finally, the diameter of each load plate unit 78 may be substantially the same as, less than, or greater than, the radial width of the annular surface of the backing wheel 38.

Upon completion of the polishing operation, drive of the polishing wheel assembly 36, and delivery of polishing material thereto, are interrupted; the introduction of fluid under pressure into the collar 64 is interrupted; the spindle assemblies 50 are retracted and the pressure discs 68 withdrawn from engagement with the load plate units 78; and the load plate units 78 and work pieces affixed thereto are removed from the polishing wheel assembly 36.

While there has been shown and described a preferred embodiment of the present invention, it will be understood by those skilled in the art that various rearrangements and modifications may be made therein without departing from the spirit and scope of the invention. Also, it will be appreciated that in the drawings certain elements--for example, the cloth 40 and the workpieces 94--, have been exaggerated from the true scale for sake of clarity of illustration.

Claims

I claim:

1. In a polishing machine having framework, a polishing wheel assembly mounted on the framework on a vertical axis, means for rotating the polishing wheel assembly, at least one vertical spindle assembly supported from the framework above the polishing wheel assembly, a generally horizontal circular load plate unit having a continuous uninterrupted lower planar surface and adapted to have workpieces affixed to the lower surface thereof for engagement with the polishing wheel assembly, and means for selectively establishing interengagement between the spindle assembly and the load plate unit, the improvement which comprises said load plate unit having an inlet spaced from said lower surface for receiving fluid, said load plate unit having passageway means entirely spaced from said lower surface in nonintersecting relation thereto and communicating with said inlet and opening outwardly of said unit to accommodate discharge of fluid from said inlet through said unit for effecting cooling thereof, and said spindle assembly having fluid transmission means for receiving fluid and transmitting the same to said inlet.

2. The improvement of claim 1 wherein said load plate unit is comprised of two plate sections secured together in spaced relation to define said passageway means.

3. The improvement of claim 1 wherein said spindle assembly includes a lower section that projects into said inlet, and said fluid transmission means is defined by a central axial opening in said spindle assembly which communicates with said inlet and a radial opening in said spindle assembly which communicates with said axial opening and is adapted to be connected to a source of fluid under pressure.

4. The improvement of claim 3 wherein said load plate unit is comprised of upper and lower plate sections secured together in spaced relation to define said passageway means, said inlet is defined by a central axial opening in said upper plate section, and said lower section of said spindle assembly is received in said axial opening in said upper plate section.

5. The improvement of claim 4 wherein the fluid under pressure is a gas, and said upper and lower plate sections are spaced apart a predetermined distance to permit expansion of the gas as the latter is discharged through said passageway means.

6. The improvement of claim 1 wherein said interengagement means is comprised of swivel connection means, said spindle assembly includes a spindle and a tube secured axially therein and defining in part said fluid transmission means, said tube is arranged with the lower end thereof communicating with said inlet, and said spindle is formed with an annular clearance surrounding a portion of said tube to permit the latter to flex during swivel movement of said load plate unit.

7. For use in a polishing machine, a circular load plate unit having a continuous uninterrupted planar surface at one side thereof to which workpieces may be affixed, having an inlet which opens axially at the other side of said unit for receiving fluid, and having passageway means entirely spaced from said planar surface in nonintersecting relation thereto and communicating with said inlet and opening outwardly of said unit to accommodate discharge of fluid from said inlet through said unit for effecting cooling thereof.

8. A load plate unit as set forth in claim 7 which is comprised of two plate sections secured together in spaced relation to define said passageway means.

9. A load plate unit as set forth in claim 8 which is adapted for use with a gas under pressure, and wherein said plate sections are spaced apart a predetermined distance to permit expansion of the gas as the latter is discharged through said passageway means.