US 2671993 A
Description (OCR text may contain errors)
Mardl 1954 v s. P. JONES ET AL 3 CONCAVE GRINDER Filed Sept. 18, 1952 INVENTORS, SAMUAL R JONES @RALPH w RICHARDS W /A ml Mr ATTORNEYS Patented Mar. 16,1954
UNITED STATES rs'rsnr OFFICE Samuel P. @5223: Richards,
West Winfield, N. Y...v assignors' to Utica Drop Forge 8: Tool Corporation, a corporation of New York Application September 18, 1952, Serial No. 310,242
This invention relates to surface grinding machines in general, and relates more specifically to grinding and polishing true concave surfaces to specific size tolerances.
An object of this invention is to provide apparatus for removing surface metal on a concave surface to close tolerances.
Another object of this invention is to reduce inaccurate grinding caused by gradual tool and die wear.
Other objects and a fuller understanding of the invention may be had by referring to the following description and claim, taken in conjunction with the accompanying drawings, in which:
Figure 1 is a schematic illustration of a conventional belt grinding and polishing machine adapted by the provisions of this invention to accurately remove the surface of concave workpieces over long periods of production; and
Figure 2 is a section taken along the line 2--2 of Figure 1, but with the shoe and workpiece closed into work relationship.
In Figure 1 of the drawings the grinding machine embodying the principles of this invention is illustrated diagrammatically. The grinding machine comprises an endless belt 10 running in a closed path about a drive wheel I l and and idler wheel I2. An endless abrasive belt 13 runs in a closed endless path about a guide wheel H and a guide wheel I5. The grinding machine is provided with ways I8, which are vertical in the particular type of machine illustrated. A carriage I9 operates in a vertical reciprocal path guided by the ways l8. Mechanism is provided for moving the carriage It in either direction on the ways, but the driving mechanism is conventional and may be varied as desired for hand operation or automatic power feed. Accordingly, the carriage driving mechanism is not illustrated in the drawings.
The drive belt I0 passes over the top of the wheels l4 and I5, and provides a driving action for the endless abrasive belt by the frictional contact with the abrasive belt. There is no direct mechanical drive of either of the wheels It and i5, and accordingly the endless belt l3 can be stalled if excessive friction occurs.
The endless abrasive belt i3 is guided over two idler wheels 2! and 22 and passes around the carriage it. Usually, prior to this invention, a fixed shoe member is provided on the carriage ill to act as a pressing shoe to force the abrasive belt into a concave workpiece. According to this invention, there has been provided a roller shoe 25 carried by the carriage Hi. 'The roller shoe 25 can best be observed in Figure 2 of the drawings. The workpiece, which is referred to by reference character 21, may be any concave piece, but is illustrated as an airfoil blade having the concave surface thereof tapered. This invention provides the only known method for obtaining good internal grinding of a concave tapered surface. The roller shoe 25 is provided in conical tapered form. However, the bearings which support the roller shoe on the carriage l9 are adapted to hold the bottom surface of the shoe 25 substantially level. Therefore, the use of tapered shoe 25 does not require particular change of idler wheels 2| and 22 from standard practice wherein a stationary shoe is employed. The use of a cylindrical roller shoe 29 will not require any change of the standard idler wheels 2| and 22, either.
A base fixture 20 is provided to removably hold a workpiece fixture 26 with the workpiece 21 clamped therein. The workpiece fixture is preferably held in a horizontal level position under the carriage [9. In Figure 1 of the drawings there is illustrated in dotted lines the path of the abrasive belt l3 whenever the carriage I9 is forced downwardly to bring the roller shoe into the cavity of the workpiece. The full lines illustrate the upper position of the carriage 19. The workpiece is changed when the carriage is in the upper position. Figure 2 of the drawings illustrates the carriage in the lower, or work position, wherein the grinding surface of the belt is brought into contact with the workpiece.
Because lowering and raising of the carriage l9 will cause the belt l3 to tighten about the wheels l4 and IS, the wheel H has been mounted on a pivot support arm 16 held taut by a spring ll. Therefore, as the carriage I9 is lowered, the wheel M can move inwardly towards the carriage, and as the carriage is raised, the wheel 14 can swing back to a position removed from the carriage and take up the excess belt.
By the provision of the roller shoe of this invention, particularly in the tapered form illustrated in the drawing, excessive guide shoe wear has been practically eliminated and internal grinding of concave surfaces is readily accomplished even when tapered in form. With fixed guide shoes as provided by the prior art, wear of the belt upon the guid shoe quickly caused a slight change in the contour of the guide shoe which resulted in airfoil surfaces not quite true. With modern jet propulsion aircraft depending more and more on close tolerances in production,
3 the advantage of the roller sho 25 will become readily apparent.
Although the invention has been described in its preferred form with a certain degree of particularity, it is understood that the present disclosure of the preferred form has been made only by way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing from the spirit and the scope of the invention as hereinafter claimed.
What is claimed is:
A grinding machine for grinding curved surfaces, comprising, an endless abrasive belt, first and second roller guide means, a roller pressure shoe, said first and second roller guide means and said pressure shoe positioned with the axis thereof laterally spaced, second and third roller guide means laterally spaced and elevated with respect to said first and second roller guide means, said abrasive belt passing over and around the second and third roller guide means, over said first and second guide means and under said roller pressure shoe in a closed loop, shiftable mounting means for one of said second and third roller guide means, means to move the pressure shoe in a vertical reciprocable path to drive the abrasiv belt against a workpiece, said shiftable mounting for said roller guide means taking up the slack of said abrasive belt, first and second drive roller guide means, an endless drive belt looped around said first and second drive roller guide means and passing against the tops of said second and third roller guide means, and drive means for said endless drive belt, said drive belt imparting a slippable drive to said abrasive belt by frictional contact.
SAMUEL P. JONES.
RALPH W. RICHARDS.
References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 294,766 Coy Mar. 11, 1884 543,155 Linn et a1. July 23, 1895 1,082,670 Wysong Dec. 30, 1913 1,288,908 Johnson Dec. 24, 1918 1,844,165 Kabelac Feb. 9, 1932 2,145,418 Herchenrider Jan. 31, 1939 2,431,795 Elmes Dec. 2, 1947 2,575,656 Coe et a1 Nov. 20, 1951