US3286407A - Abrasive finishing apparatus - Google Patents

Description

Nov. 22, 1966 G. H. LOCKWOOD 3,

ABRASIVE FINISHING APPARATUS Filed March 4, 1964 INVENTOR.

George H. loclzwood H eq 7 United States Patent ration of Delaware Filed Mar. 4, 1964, Ser. No. 349,303 7 Claims. (Cl. 5133) I This invention relates to an abrasive finishing apparatus and, more particularly, to apparatus arranged to refine a surface of revolution by the abrasive process.

In the art of honing annular surfaces, such as the grooves in the races of ball bearings, it has been found that, for a reason not clearly understood, when one attempts to speed up the finishing operation by removing large amounts of material, the surface tends to take a shape which is not entirely concentric with the axis of revolution. This condition i known as being out of round and is a serious limitation on the ability to speed up production, particularly in automatic machines of this type. These and other difiiculties experienced with the prior art devices have been obviated in a novel manner by the present invention.

It is, therefore, an outstanding object of the invention to provide an abrasive finishing apparatus in which the use of high rates of stock removal does not result in an out-of-round condition in the workpiece.

Another object of this invention is the provision of an apparatus for honing annular grooves or the like, wherein the work is carried on at a high speed and wherein the finished surface is perfectly concentric with the axis of the workpiece.

A further object of the present invention is the provision of an apparatus for honing which gives a fine finish to the workpiece, despite a high production rate.

It is another object of the instant invention to provide a honing machine having a means for improving the concentricity of the finished surface, which means is simple and rugged and which is capable of along life of useful service with a minimum of attention.

With these and other objects in view, as will be apparent to those skilled in the art, the invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto.

The character of the invention, however, may be best understood by reference to one of its structural forms, as illustrated by the accompanying drawings in which:

The single figure is a partially sectioned front elevational view of an apparatus embodying the principles of the present invention.

Referring to the drawing, the apparatus, indicated generally by the reference numeral 10, is shown as a honing apparatus of the type shown and described in the copending patent application of Lockwood, Serial Number 247,094, filed December 26, 1962, for Apparatus for Honing an Annular Surface, now Patent No. 3,178,858. The principle of operation is that the workpiece remains fixed, While the honing stones are rotated about the axis of the workpiece and, by a reciprocation of the honing head, the stones are rotated about the center of curvature of the groove. The apparatus is provided with a base 11 from which extend four vertical abutments 12, 13, 14, and 15. Fastened to the base at the rear of the machine and extending over the rest of the apparatus is a mounting block 16.

Mounted on the abutment 12 is a platen 17 having a flat, vertical face 18 which is very carefully machined and against which is pressed one end of a workpiece 19 which, for the purposes of illustration, is shown as the inner race of a ball bearing, which race has a groove 21 to be finished by honing.

Extending through the abutment 13 is a bore 22 whose "ice axis is aligned with the axis of the workpiece 19, particularly of its inner bore 23. The bore 22 slidably carries a ram 24 which, in turn, carries a spindle 25 on which is mounted a drive pulley 26. On the end of the spindle 25 closest to the workpiece 21 is carried a head 27 on which are pivotally carried at least a plurality of arms 28. Mounted at the outer end of each arm 28 is a honing stone 29 having a suitable curved inner surface for formation and finishing of the groove 21. Within the head 27 are provided springs 31 for biasing the arms 28 to press the stones 29 inwardly against the surface of the groove 21. The interior of the ram 24 is provided with a cylinder 32 in which is slidably carried a piston 33 whose rod 34 is connected to the upper part of the abutment 14. Suitable hydraulic connections are made to the cylinder to provide for movement of the ram 24 longitudinally of the axis of the workpiece. Extending through the head 27, the spindle 25, and the ram 24 is a rod 35. The end of the rod 35 adjacent the workpiece 19 is provided with a clamping plug 36 having a reduced portion 37 adapted to engage the workpiece 19 and hold it firmly against the platen 17. The diameter of the reduced portion 37 is only slightly less than the diameter of the inner bore 23 of the workpiece, so that the surface 37 engages the surface of the bore 23 and the clamp plug engages the end of the workpiece facing toward the head 27. The platen 17 and the clamping plug 36 form a fixed workhead.

The rod 35 extends through the abutment 15 and has mounted on it a piston 38 which is slidably carried in a cylinder 39 formed in the abutment. Suitable hydraulic connections are made for moving the piston 38 within the cylinder 39, on occasion. At its outer end, the rod 35 carries a collar 41. Firmly fixed to the right-hand end of the ram 24 is a plate 42 in which is slidably carried a rod 43 having a rounded head 44. The rod 43 is slidably carried in a bearing 45 mounted on an extension 46 of the mounting block 16. Bolted to the end of the rod 43 opposite the head 44 isan arm 47 having a bore 48 through which the rod 35 slides. Also pivoted on the mounting block 16 is an arm 49 having at its lower end a hardened metal insert 51 adapted to engage the head 44 of the shaft 43. At an intermediate position, the arm 49 is provided with a cam follower 52. The mounting block 16 is also provided With an extension 53 on which is rotatably carried a shaft 54 carrying a cam 55. The shaft 54 and the cam 55 are driven by a motor (not shown).

The operation of the apparatus will now be readily understood in view of the above description. Pressure oil provided at the right-hand side of the piston 38 in the cylinder 39 forces the rod 35 to the left so that the radial surface of the plug 36 presses against the workpiece 19 and holds it tightly against the vertical surf-ace 18 of the platen 17 This clamping is such as to prevent the workpiece 19 from rotating and yet takes place without any distortion of the workpiece, since the clamping pressure is equal around the periphery of the workpiece. By means of the pulley 26, the spindle 25 and the head 27 are rotated about the axis of the workpiece and the springs 31 press the honing stones 29 against the surface of the groove 21 to form the finished surface. The ram 24 is reciprocated by the action of the cam 55 on the plate 42. The dimensions selected are such that the honing stones 29 are rotated about their centers of curvature in the manner shown and described in Patent No. 3,178,858, discussed above. As the ram 24 reciprocates, the plate 42 slides over the rod 43, the rod 43 taking part in this action. When the workpiece is finished and is ready to be exchanged for another unfinished workpiece, suitable hydraulic fluid is admitted into the cylinder 39 to withdraw the rod 35 axially away from the workpiece to loosen it and permit its removal. At that time, the ram 24 has been subjected by the cylinder 32 to an extended retraction also, so that the stones 29 and the arms 28 are removed from the workpiece to permit its removal.

Now, the cam 55 is rotated at a selected speed and the ram 24 reciprocates back and forth every time the cam makes one revolution. When the portion of greatest throw of the cam extends to the right, the ram 24 is moved to the right. That is to say, the cam presses against the cam follower 52 which, in turn, presses the insert 51 of the arm 49 against the head 44 of the rod 43, so that the rod is held tightly against the plate 42 and moves to the right with the ram 24. The rod 43 moving to the right carries the plate 47 and, eventually, the plate contacts the collar 41 on the rod 35. The contact with the rod is selected to be very slight and only momentary, so that the rod 35 is struck a blow and, despite the presence of oil at the right side of the piston 38, the rod is pulled slightly to the right, loosening the pressure of the plug 36 against the workpiece. Momentarily, therefore, the workpiece is free to rotate. The head 27 continues to rotate and the reduced portion 37 acts as a support for the workpiece. The stones 29, by their abrasive action, cause the workpiece to rotate slightly. The ram 24 is moved to the left again and almost immediately the rod 43 and the plate 47 are withdrawn from the collar 41 so that the clamping plug 37 is moved back into clamping position against the workpiece 19. The slight release of the clamp plug 36 in this manner, however, permits the workpiece 19 to rotate and index slightly during the period of release. The result is that, despite high pressures of the honing stones 29 against the surface of the groove 21 and consequent high material rate removal, the finished surface of the groove is not out-of-round. A perfectly smooth concentric finished annular surface is obtained.

It is obvious that minor changes may be made in the form and construction of the invention without departing from the material spirit thereof. It is not, however, desired to confine the invention to the exact form herein shown and described, but it is desired to include all such as properly come Within the scope claimed.

The invention having been thus described, what is claimed as new and desired to secure by Letters Patent is:

1. Apparatus for honing an annular surface of a workpiece, comprising (a) a fixed workhead having a clamp for holding the workpiece against rotation,

(b) a toolhead mounted adjacent the workhead and having a spindle which is subject to rotation about and reciprocation substantially along the major axis of the said surface, the toolhead pressing a tool against the surface with a predetermined pressure, and

(c) means operative on the said clamp for releasing the workpiece occasionally for a short period of time to permit slight rotation thereof.

2. Apparatus as recited in claim 1, wherein the said means includes an eccentric member which provides synchronous reciprocation of the spindle.

3. Apparatus as recited in claim 1, wherein the clamp is mounted on a rod which extends through the spindle and is provided with an actuator for moving the rod longitudinally to clamp and unclamp the workpiece.

4. Apparatus as recited in claim 3, wherein the rod is provided with a collar and wherein the said means strikes the collar a blow on occasion to overcome the operation of the actuator and to release the workpiece.

5. Apparatus as recited in claim 4, wherein the means is time-d to strike the collar during each reciprocation of the spindle.

6. Apparatus as recited in claim 5, wherein a second rod is mounted parallel to the clamp rod and extends through a portion of the toolhead, the second rod having a head on one end and a plate at the other in position to strike the said collar, and wherein an eccentric is provided which operates during each reciprocation of the spindle to move the head of the second rod relative to the said portion of the toolhead so that the rod reciprocates with the spindle and the plate strikes the collar.

7. Apparatus for finishing an annular surface of a workpiece by abrasion, comprising (a) a workhead having a clamp for holding the workpiece,

(b) a toolhead mounted adjacent the workhead and having a spindle which is subject to rotation about and reciprocation substantially along the major axis of the said surface, the toolhead pressing a tool against the surface with a predetermined pressure, an

(c) means operative on the said clamp for releasing the workpiece occasionally for a short period of time to permit a slight rotation thereof.

References Cited by the Examiner UNITED STATES PATENTS 3,178,858 4/1965 Lockwood s1 33 LESTER M. SWINGLE, Primary Examiner.

Claims (1)

1. 7. APPARATUS FOR FINISHING AN ANNULAR SURFACE OF A WORKPIECE BY ABRASION, COMPRISING (A) A WORKHEAD HAVING A CLAMP FOR HOLDING THE WORKPIECE, (B) A TOOLHEAD MOUNTED ADJACENT THE WORKHEAD AND HAVING A SPINDLE WHICH IS SUBJECT TO ROTATION ABOUT AND RECIPROCATION SUBSTANTIALLY ALONG THE MAJOR AXIS OF THE SAID SURFACE, THE TOOLHEAD PRESSING A TOOL AGAINST THE SURFACE WITH A PREDETERMINED PRESSURE, AND (C) MEANS OPERATIVE ON SAID CLAMP FOR RELEASING THE WORKPIECE OCCASIONALLY FOR A SHORT PERIOD OF TIME TO PERMIT A SLIGHT ROTATION THEREOF.

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