US 3099904 A
Description (OCR text may contain errors)
Aug. 6, 1963 R. M. BELL MECHANICAL DEVICE Filed Oct. 10, 1960 INVENTOR.
RAMSAY M. BELL ATTORNEYS United States Patent 3,tl99,9-4 FIE1WKAL DEVICE Ramsay M. Bell, Schoolcraft, Mich, assigns: to Hammend Machinery Builders, Inc, Kalamazoo, Mich, a corporation of Michigan Filed Get. 10, 1960, Ser. No. 61,416 Claims. (Cl. 51-141) This invention relates in general to a grinding machine and, more particularly, to a type thereof having a perforate belt and platen through which a coolant fluid, which may be either liquid or gaseous, or a cutting oil, is moved with a minimum of obstruction so that satisfactory grinding can be performed with a minimum of overheating. This application is a continuation-in-part of application Serial No. 762,163, filed September 19, 1958.
The use and construction of belt-type grinders have long been familiar and many specific forms have been used. It is well known that a belt-type grinder is capable of performing certain types of grinding operations in a much more eificient and convenient manner than other types of grinders, such as the disk grinder for exmple, particularly because the platen and belt can be formed to fit or otherwise suit certain types of for-med workpieces.
Among those obstacles which have apparently impeded the development of .a belt-type grinding machine are the proper control and the adequate supply of coolant or cutting oil to the grinding zone. Previous attempts to effect acceptable grinding operations with a belt grinder have not provided sufiicient flow of coolant or cutting oil to the grinding zone for optimum grinding action. Particularly, the prior art practice of supplying coolant to the edges of the belt and relying on the belt to carry the coolant to the grinding zone did not elfect a sufficient supply of coolant and overheating resulted.
Accordingly, a primary object of this invention has been provision of a grinding machine utilizing a belt-type abrasive element which is provided with improved means for supplying coolant or cutting oil to the grinding zone.
A further object of this invention has been the provision of a belt-type grinder wherein a sufliciently continuous and adequate supply of coolant or cutting oil can be maintained in the zone between the workpiece and the belt of the grinding machine to efiect the grinding operation with optimum results.
A further object of this invention has been the provision of a belt-type grinding machine, as aforesaid, which is extremely easy to operate, which requires a minimum of maintenance, which is sturdy and reliable in construction and which performs accurately.
A further object of this invention has been the provision of a construction for a belt-type grinder, as aforesaid, wherein the reach of the belt by which the grinding operation is performed can be caused to operate on non-linear surfaces of various shapes which may be convex and/or concave, such non-linearity being either lengthwise or crosswise of the belt.
Other objects and purposes of the invention will become apparent to persons familiar with this type of equipment upon reading the following specification and examining the accompanying drawings, in which:
FIGURE 1 is a broken, front elevational view of that portion of a belt-type grinding machine embodying, and pertinent to, the invention.
FIGURE 2 is a broken, fragmentary side elevational view of said grinding machine.
FIGURE 3 is an enlarged sectional view taken along the line llllll of FIGURE 1.
FIGURE 4 is a broken sectional view taken along the line IV-IV of FIGURE 3.
FIGURE 5 is a sectional view taken along the line 3,99,%4 Patented Aug. 6, 1963 VV of FIGURE 2 and showing a modified platen construction.
FIGURE 6 is a sectional view taken the line VIVI of FIGURE 5 and rotated clockwise.
FIGURE 7 is a fragmentary top view of a modified grinding machine embodying the invention.
For convenience in description, the terms upper, lower and derivatives thereof will have reference to the grinding machine as appearing in FIGURES 1 and 2, unless otherwise stated to the contrary. The terms inner, outer and derivatives thereof will have reference to the geometric center of said grinding machine and parts associated therewith. The terms front and rear will have reference, respectively, to the left and right sides of the said machine as appearing in FIGURE 2.
General Description The objects of the invention, including those set forth above, have been met by providing a grinding machine having a pair of spaced and axially parallel rollers around which an endless belt extends, one reach of said belt being, in the embodiment here illustrated and described, disposed in a substantially vertical plane and having a belt-supporting platen adjacent its inner side and a worksupporting table adjacent its outer side. Said belt is of very uniform thickness throughout its length, is perforated so that a coolant or cutting oil can pass therethrough with a minimum of obstruction, and has an abrasive coating on its outer surface of substantially uniform thickness. The platen has a perforate region which is located substantially opposite and extends slightly above the work as it faces the platen. The perforated portion of said platen defines one side of a chamber which is defined on the remaining sides by the walls of a casing secured to said platen.
Mechanism including a collecting basin and a pump are provided for receiving the coolant or cutting oil as it moves away from the grinding zone and returning same under pressure to the chamber so that it will pass again through the perforations and back into said grinding zone.
Detailed Construction The belt-type grinding machine 10 (FIGURES 1 and 2), herein selected to illustrate the invention, may have a basin construction similar to the belt-type grinder disclosed in patent application Serial No. 738,869, filed May 29, 1958, entitled, Machine Tool, and assigned to the assignee of this application. More specifically, the grinding machine 10 is comprised of a central housing 11 supported upon the upper portion of a pedestal 12 which also supports a driving motor 13a below said housing. An upper pulley 16 is vertically adjustably supported upon the housing 11 and a lower pulley 17 is supported upon the shaft 18 of the motor 13- for rotation thereby. The pulleys 16 and 17, which are axially parallel and arranged so that the lower pulley 17 is directly under the upper pulley 16, are encircled by an endless belt 19 of uniform thickness.
Said belt 19 (FIGURE 3) is preferably fabricated from a strip of woven fabric having 'a plurality of closely spaced openings 21 through which the coolant or cutting oil can easily pass. These openings should be arranged to cover the entire surface of the workpiece substantially uniformly with coolant or cutting oil, but any random or geometric pattern capable of doing this is acceptable. The perforations will normally extend over the entire area of the belt, but should at least cover a band along said belt as wide as, or slightly wider than, the width of the workpiece. The openings should be arranged to cover an area Some. what wider than the workpiece if it is desired to reciprocate the workpiece crosswise of the belt during the grinding process. The flow of coolant through the belt is primarily controlled by the perforations provided, as hereinafter described, in the platen behind the belt so that, for commercially acceptable purposes, it is normal- -ly preferable to perforate the entire belt. The outer surface 22 of the belt 19 has a coating of abrasive material, such as aluminum oxide, silicon car-bide or diamond bort, which may be affixed to said belt in any conventional manner.
The housing 111 has a relatively fiat platen 26 (FIG- URE 2) on its front surface which lies closely adjacent to and is parallel with the inner surface 27 of the front reach 28 of the belt v1'9, which reach preferably moves downwardly. Said platen 26, which may be generally similar to the platen shown in Patent No. 2,562,229, has a plurality of closely spaced, relatively small openings 29 located in the portion of said platen opposite the grinding position of the workpiece. Said openings cover an area slightly wider than the surface of the workpiece engaged by the belt. This area must be somewhat wider if crosswise reciprocation of the workpiece is desired. In a vertical direction the area of openings .29 commences at, or slightly above, the lower edge of the workpiece and extends somewhat above the upper edge of the workpiece. The extent of the openings above the upper edge of the workpiece will depend somewhat on the freeness (rate at which an aqueous liquid can pass through the belt under moderate'pressure) of the belt. In any event the-area of openings will be sufiicient to enable the coolant to pass through the belt and furnish an adequate supply of coolant to all portions, including the upper portion, of the workpiece. The openings are of relatively small size in order to eflfec-t a more complete and uniform distribution of coolant being discharged against, and through, the belt.
The platen 26, will be made of any suitable material, but it should be of suflicient wear resistant properties that it will not be unreasonably abraded by the belt. Tungsten carbide is preferable although for a relatively light service other types of wear resisting materials or platings can be utilized.
The exact pattern of openings 29 in the area of the platen occupied by said openings may be readily varied as required to fit a given workpiece either by replacing the plate .26 as needed or by providing the openings in a suitable insert 26a removable from the platen.
As shown in FIGURES 3 and 4, a casing 31 of shallow depth is secured to the rear side of the platen 26 by means, such as the bolts 3-2, and combines with the perforate region of the platen 26 to define a small chamber 33, which communicates with the openings 29. The chamber 33 is connected by a conduit 34 to a pump 37, which may be of the positive displacement type. Said pump 37 has its inlet 38 connected to a low point in a collecting basin 39 which is disposed beneath and surrounds the lower pulley 17, as well as the lower portion of the belt 19. The basin 39 extends upwardly and forwardly a suflicient distance to catch the coolant which is moved downwardly from the grinding zone by gravity and/or the downward movement of the front reach 28.
A work support table 42 is preferably adjustably supported upon the pedestal .12 by means such as the arm 43 so'that its rear edge 44 is close to but spaced from the front or outer surface 22 of the front reach 28.
Operation With the grinding machine 10 assembled as shown in FIGURES -1 and 2, it is made ready for use by energizing the motor 13 and pump 37. A workpiece 47 is placed upon the table 42 and advanced toward the outer surface 22' of the front reach 28 of the belt 19 until it is just touching said front reach 28. The pump 3-7 causes the coolant t flow from the chamber 33 through the openings 29 and 21 toward and against the workpiece 47 and fresh coolant is constantly supplied thereto partly by 4 direct flow through the belt adjacent the workpiece and partly through the belt above the workpiece from which location it is carried into the grinding zone by the motion of the belt. From the grinding zone the coolant partly drops from gravity and partly moves with the belt 19 downwardly into the collecting basin 39.
The pump 37 receives the coolant collected by the basin 39 and moves it upwardly through the conduit 34 back into the chamber 33 under sufficient pressure that such coolant will again flow through theopenings 29 in the platen 26 and thence through the openings 21 in the belt 19.
Platens and associated structure embodying the invention may be contoured in a wide variety of specific shapes to handle work of different shapes. For example, as shown in FIGURES 5 and 6, a platen 51 having a concave front surface 52 may be provided between the main belt supporting rollers, such as those shown at 16 and 17 in FIGURE 1. The front reach 56 of the grinding belt 57 (FIGURE 6), which may be substantially identical in construction with the belt 19, may be urged against the front surface 52 of said platen 51 by the workpiece 58 which is supported upon the table 59. Means, such as the roller shown in broken lines at 6!) in FIGURE 6, may be rotatably mounted upon the table 59 for assist-ing in holding the belt 57 against the platen 51.
The portion of the platen 51 opposite the workpiece has a plurality of openings 61 (FIGURE 6) which communicate between the openings 62 in the belt 57 and the chamber 63 behind the central portion of said platen 51. Accordingly, by using the alternate platen structure 51 it is possible to produce convex surfaces by means of a belt-type grinder.
FIGURE 7 illustrates a further alternate platen 66 having a convex outer surface '67 around which the belt 68 extends. A pair of idler rollers '69 and 79 may be used if desired to assist in holding the belt in place with respect to the platen. A guide wheel 72, which is coaxial with, and of a slightly larger radius than, said convex surface 67, may also if desired be provided adjacent to the platen '66 and between said rollers 69 and 70. The alternate platen has a chamber 75 in the central portion thereof which communicates with the inlet conduit 71 and with openings through the outer surface of the platen 66 in substantially the same manner as set forth with respect to the structure shown in FIGURE 3. Accordingly, a machine having the alternate platen '66 can be used for providing concave surface in a workpiece by the grinding process.
While in each of the embodiments shown the belt is in a vertical position, and in at least the embodiments of FIGURES l to 6 inclusive some reliance is placed upon gravity to return the coolant to the low pressure side of the pump provided for circulating same, it will be recognized that the apparatus of the invention may be readily modified to operate in any other desired position according to the purposes to be served and reference herein to particular positions will be understood as used only in connection with the particular embodiment here chosen to illustrate the invention and not as limiting.
Although particular preferred embodiments of the invention have been disclosed above in detail for illustrative purposes it will be understood that variations or modifications of such disclosure, which lie within the scope of e appended claims, are fully contemplated.
What is claimed is:
l. A grinding machine comprising: an endless, perforate abrasive belt and pulley means supporting same for movement in a closed path; a stationary, rigid platen having a surface adjacent the inner side of said belt and extending along a portion of said path, said platen having a perforate region between its ends which said belt overlies, said perforate region being of substantial extent and having a multiplicity of perforations which are spaced apart both laterally and lengthwise with respect to the belt; means including said region of said platen defining a chamber communicating with the perforations in said platen; a work support adjacent to the outer side of said belt, said perforate region extending from adjacent said work support to a point spaced a substantial distance therefrom; means for moving a fluid into said chamber under pressure so that said fluid flows through the perforations in said region of said platen and through the perforations in the belt into contact with the work supported on said work support.
2. A grinding machine comprising: an endless, perforate abrasive belt; vertically spaced driving and supporting pulleys for said belt; a work support adjacent the downwardly moving reach of said belt; a stationary, rigid platen having a belt engaging surface behind said downwardly moving reach of said belt, said platen having a perforate region opposed to said work support, said perforate region extending from adjacent said work support to a point spaced upwardly a substantial distance therefrom, said perforate region being of substantial vertical extent and having a multiplicity of vertically and horizontally spaced perforations; means including said region of said platen defining a chamber; and means for supplying a liquid under pressure to said chamber so that the liquid flows through the perforations in said region of said platen and through the perforations in the belt into contact with the work supported on said work support; and a collecting receptacle located below said work support and extending on both sides of said downwardly moving reach of said belt for receiving liquid travelling downwardly thereon.
3. A grinding machine according to claim 2 wherein said platen has a non-planar surface which includes said perforate region whereby the workpiece may be ground to have a corresponding non-planar surface by urging same against said non-planar surface of said workpiece.
4. A grinding machine according to claim 2 wherein said platen has a convex surface which includes said perforate region; and a pair of rollers located on either side of said platen and rotatable about parallel axes for urging the belt to move along said surface.
5. A grinding machine according to claim 2, in which said collecting receptacle is an open-topped basin, the lowermost pulley being disposed directly above the bottom Wall of said basin and both the upwardly moving reach and the downwardly moving reach of said belt extending upwardly from said basin so that liquid on said belt is free to fall by gravity into said basin; and a pump for removing liquid from said basin and supplying same to said chamber.
References Cited in the file of this patent UNITED STATES PATENTS 1,408,851 .Weiss Mar. 7, 1922 1,993,543 'Egger Mar. 5, 1935 2,562,229 'Bell July 31, 1951 2,594,647 Hendrickson Apr. 29, 1952 2,761,256 OConnor Sept. 4, 1956 2,778,169 Ball Jan. 22, 1957