US2860622A

US2860622A - Grinding machine having rotatable wheel dressing tool

Info

Publication number: US2860622A
Application number: US611227A
Authority: US
Inventors: Glenn A Hider
Original assignee: Gleason Works
Current assignee: Gleason Works
Priority date: 1956-09-21
Filing date: 1956-09-21
Publication date: 1958-11-18
Anticipated expiration: 1975-11-18

Description

Nov. 18, 1958 G. A. HIDER 2 GRINDING MACHINE HAVING ROTATABLE WHEEL DRESSING TOOL Filed Sept. 21, 1956 2 Sheets-Sheet 1 INVENTOR.

GLENN A. H] DER Qua/Z25 ATTORNEY Nov. 18, 1958 G. A. HIDER GRINDING MACHINE HAVING ROTATABLE WHEEL DRESSING TOOL Filed Sept. 21, 1956 2 Sheets-Sheet 2 in I 56 I F|G 5 IT! 29 l 28 United States Patent GRINDING MACHINE HAVING ROTATABLE WHEEL DRESSING TOOL Glenn A. Hider, Penfield, N. Y., assignor to The Gleason Works, Rochester, N. Y., a corporation of New York Application September 21, 1956, Serial No. 611,227 8 Claims. (Cl. 125-11) The present invention relates to grinding machines and is especially concerned with the mounting means for the tools employed on such machines for dressing the grinding wheels thereof.

Diamond-tipped tools are frequently used for this purpose, and it is known practice to periodically rotate such a 'tool through a small angle to thereby present a new face of the diamond to the grinding wheel. In this way wear is distributed around the diamond causing the life of the tool to be prolonged, and the facets worn on the diamond are prevented from becoming so enlarged as to impair wheel-dressing efficiency.

,An object of the present invention is a rugged mechanism for periodically turning the tool by uniform increments. Such mechanism includes an actuator which will upon each operation thereof advance a rotatable member through a simple fraction of a revolution, and a connection between the-rotatable member and the tool arranged to advance the tool through a different angle than the member. This difference of angle is such that the tool repeats its position only after it has made a number of complete revolutions; and because of this, after each advance, the edge of a facet of the tool, rather than a flat surface thereof, is presented to the wheel. As a result, a more efficient wheel-dressing action is obtained and the formation of wide facets on the tool, which lead to ineflicient dressing action, is prevented.

In certain conventional machines the dressing tool is periodically advanced into the path of the rotating abra-- sive wheel, and either the tool or the wheel is then moved to cause the tool to traverse and thereby dress the active surface of the wheel, after which the tool is retracted from the path of the wheel. The present invention provides for the tool to be rotatively advanced once for each cycle of its advance and retraction with respect to the path of the wheel, so that for each dressing operation a fresh edge of the tool is presented to the wheel.

The foregoing and other objects and advantages will appear from the following description made with reference to the accompanying drawings illustrating an application of the invention to a cutter sharpening machine. In the drawings:

Fig. 1 is a front view, partly in vertical section, of the parts of the machine related to the invention;

Fig. 2 is a detail sectional view in plane 2-2 of Fig.

Fig. 3 is a diagram of the hydraulic system for moving the dresser tool;

Fig. 4 is a vertical sectional view through the dressing tool and its supporting head, in the broken plane indicated by line 4 4 of Fig. 5; and,

Fig. 5 is a sectional view in plane 55 of Fig. 4.

The machine illustrated fragmentarily in Fig. 1 may be of the general type disclosed in Patent No. 2,224,959 to C. T. Galloway, and comprises a frame on which is supported a wheel head 11. In this head is journaled a spindle 12 supporting a grinding wheel 13 for rotation about axis 14. The head is swingable on a horizontal slide, not shown, about a vertical axis 15, to thereby pass the active conical surface 16 of wheel 13 back and forth over a workpiece, which also is not shown and which in this case is a cutter to be sharpened. The head and its supporting horizontal slide are periodically moved back and forth in the direction of arrow 17 to cause the dressing tool to traverse the surface 16.

This tool comprises a diamond tipped element 18 and a holder 19, the element being secured in coaxial position in the holder by a set screw 21. Upon loosening of the set screw the element 18 may be adjusted along its axis, 22, by turning a screw 23 which is threaded into the holder and has a conical tip engaging the element 18. The

tool

18, 19 is supported on a pair of spaced coaxial ball-type anti-friction bearings 24 for rotation about axis 22. The inner races of these bearings fit the cylindrical shank of holder 19 and are spaced by a sleeve 25, while the outer races fit into a flanged tubular part 26 and are spaced by a sleeve 27. Tubular part 26 constitutes a part of tool head 28, its flange being secured to the head proper by screws, not shown. As shown in Fig. 1 the axis 22 is slightly inclined to a perpendicular from the adjacent active surface 16 of the wheel.

For the purpose of effecting a step-by-step rotation of

tool

18, 19, a piston 29 is arranged to reciprocate in a cylinder bore 32 in the tool head provided with sealing rings 31 and which is pivoted to it by a pin 33. The pawl is held engaged with a sleeve-shaped ratchet wheel 35 by a plunger 36 backed by a spring 37 and retainer plug 38. As shown, the pawl is disposed in a slot 39 in the piston H 29, and a key 41 projects into this same slot to prevent the piston from turning in the cylinder bore 32. Retro' gression of the ratchet wheel, i. e. clockwise motion in Fig. 5, is prevented by a holding pawl 42 which is slidable in the tool head and is backed by a spring 43 which is retained by a cap 44. This cap, which also retains the piston 29, is secured to the tool head 28 by screws 45, one of which is shown in Fig. 5. A flexible ring 46 provides a hydraulic seal between the

parts

44 and 28.

The ratchet wheel 35 is rotatable about axis 22 on the outside of the shank of a sleeve-like gear 47 which is keyed at 48 to the lower end of tool holder 19. The gear 47, the ratchet wheel and the tool holder 19, are held in assembly by a washer 49 and a screw 51. Formed integrally with the ratchet wheel is a gear 52 which is of substantially the same diameter as the gear 47. Both

gears

47 and 52 mesh with an elongated pinion 53, this pinion being rotatable on a shaft 54 that is held in the tool head by a press-fitted washer 55.

Upon each forward stroke of the piston, to the left in Fig. 3 and upwardly in Fig. 5, the ratchet wheel is' of teeth (twenty-two) throughout its length, the tool 18,

19 is turned through slightly more than nine degrees during each forward stroke of the piston, and for each complete turn of the ratchet wheel is turned through slightly more than one turn (42/41 revolutions). Moreover forty-one complete turns of the ratchet wheel are required to cause the tool to exactly repeat its position in the tool head. As a result of this, after each ratchet operation there is presented to the grinding wheel an edge of the tool tip instead of a plane facet that has been worn on the tip during a preceding dressing operation.

The dresser head 28 is secured to the rod 56 of a piston 57 which is reciprocable vertically within a cylinder 58 secured to the machine frame 10. A key 59 engages in a keyway in the piston rod to hold the head Patented Nov. 18, 1958 28. The piston is carries a pawl 34 and piston assembly against rotation. As shown in Fig. 3, the upper and lower chambers of cylinder 58 are connected respectively by

hydraulic lines

61 and 62 to a reversing valve 63, and, by

branch lines

64 and 65,- to the opposite fluid chambers of cylinder bore 32. The reversing valve is also connected to a hydraulic pressure line '66 and a return line 67 extending to a suitable pump or other source of hydraulic pressure, not shown. Prior to each wheel dressing the valve is operated to connect pressure line 66 to

' lines

62 and 65, and return line 67 to

lines

61 and 64. Accordingly the piston 57 is raised to its upper limit position shown in Figs. 1 and 3, wherein the tip of tool 18 lies in the path of surface 16 of the abrasive wheel. Simultaneously the piston 29 is moved through its return or ratchet-reset stroke, i. e. to the right in Fig. 3 and downwardly in Fig.- 5. During this stroke the pawl 42 holds the ratchet wheel against motion, and the pawl 34 rides idly over the adjacent teeth of the ratchet wheel. The actual dressing operation is then effected by movement of the abrasive wheel to the right in Fig. 1, to draw the wheel surface 16 across the tip of tool 18. At the conclusion of this operation the valve 63 is reversed to connect pressure line 66 to

lines

61 and 64, and

lines

62 and 65 to return line 67. This causes the piston to lower, retracting the dressing tool from the path of the abrasive wheel, and simultaneously moves piston 29 to the left in Fig. 3, upwardly in Fig. 5, to advance the tool rotatively in the tool head in preparation for the next dressing operation. This rotational advance of the tool during its retraction by the piston 57 assures that such advance will be completed prior to the actual dressing operation. Having now described and explained the operation of the invention, what is claimed is:

e 1. A machine comprising a tool head, a wheel dressing tool rotatable in the head, actuating means including a member rotatable step-by-step in the head about the same axis as the tool, a drive gear co rotatable with said member, a driven gear co-rotatable with the tool, and a pinion meshing with both gears.

2. A machine according to claim 1 in which the tooth number ratio of the drive gear to the pinion is diiferent from that of the driven gear to the pinion.

3. A machine according to claim 2 in which said member is a ratchet Wheel and said actuating means further comprises a member reciprocable in the head and a pawl carried thereby and engageable with the ratchet Wheel for effecting the step-by-step rotation thereof.

4. A machine comprising a tool head, a wheel dressing tool rotatable in the head, actuating means including a ratchet wheel rotatable step-by-s'tep in the head, and drive gearing connecting the ratchet wheel and the tool, said gearing being of such ratio that the angle of advance of the tool differs from that of the ratchet wheel and that the tool repeats its position only after making a plurality of turns.

5. A grinding machine having an abrasive wheel and a dressing tool for the wheel, a tool head in which the tool is mounted for rotation, the tool head and the abrasive wheel being mounted on the machine for relative motion to bring the tool and the Wheel into and ing connecting the ratchet wheel and the tool of such drive ratio that the angle of advance of the tool dilfers from that of the ratchet wheel, said gearing including a drive gear co-rotatable with the ratchet wheel, a driven.

gear co-rotatable with the tool, and a pinion meshing with both gears.

6. A grinding machine having an abrasive wheel and a dressing tool for the wheel, a tool head in which the tool is mounted for rotation, actuating means including a member rotatable step-by-step in said head through increments each of which is a simple fraction of one complete revolution, and gearing connecting said member to the tool which gearing is of such drive ratio that the angle of each rotative advance of the tool differs from that of said member, said gearing comprising a drive gear co-rotatable with said member, a driven member co-rotatable with the tool, and a pinion meshing with both gears.

'7. A machine comprising a tool head, a wheel dressing tool, axially spaced anti-friction bearings supporting the tool for rotation in the tool head, a fiuid actuated piston reciprocable in said head, a ratchet wheel rotatable in the head in coaxial relation to said bearings, a pawl actuated by the piston and engageable with the wheel for effecting step-by-step rotation thereof upon reciprocation of the piston, another pawl engageable with the ratchet wheel for preventing retrogression of the latter, a drive gear co-rotatable with the ratchet wheel, a driven gear co-rotatable with the tool, and a pinion meshing with both gears, the tooth number ratio of the drive gear to the pinion being different from that of the driven gear to the pinion.

8. A machine comprising a tool head, a wheel dressing tool, axially spaced anti-friction bearings supporting the tool for rotation in the tool head, a member reciprocable in said head, a ratchet wheel rotatable in the head in coaxial relation to said bearings, a pawl actuated by said member and engageable with the wheel for effecting step-by-step rotation thereof upon reciprocation of the member, another pawl engageable with the ratchet wheel for preventing retrogression of the latter, a drive gear co-rotatable with the ratchet wheel, a driven gear co-rotatable with the tool, and a pinion meshing with both gears, the tooth number ratio of the drive gear to the pinion being different from that of the driven gear to the pinion.

References Cited in the file of this patent UNITED STATES PATENTS 1,997,551 Romaine Apr. 9, 1935 2,628,608 Loecy Feb. 17, 1953 2,648,171 Hill Aug. 11, 1953 2,741,240 Kartscher Apr. 10, 1956