US2838886A - Compensating radial work support for an internal centerless grinder - Google Patents

Description

June 17, 1958 OVELY 2,838,886

' J. W. L COMPENSATING RADIAL WORK SUPPORT FOR AN INTERNAL CENTERLESS GRINDER Filed June 5, 1957 2 Sheets-Sheet 2 INVENTOR Me John WLOve@ /40- L jfiwhn AO/6 Maw {26 k ATTORNEY6 United States Patent COMPENSATING RADIAL WORK SUPPORT FOR AN INTERNAL CENTERLESS GRINDER John W. Lovely, Springfield, Vt., assignor to Bryant Chucking Grinder Company, Springfield, Vt., a corporation of Vermont Application has, 1957, Serial N0. 663,685 6 Claims. (0]. 51-103 This invention relates to improvements in internal grinding machines of the type wherein an annular workpiece isradially supported on a preformed outside surface for rotation in frictional relationship to supporting shoes peripherally spaced along the surface, and a tool is apas raceway rings for anti-friction bearings, must be produced at a fast rate while holding narrow tolerance limits in concentricity and diametrical dimensions. Because of prevailing economic and technological reasons the pre- 7 formed outside surfaces are allowed to have dimensional variations between successive workpieces and the internal grinder is expected to accept such workpieces at random and produce a hole therein concentric with the preformed, radially supported perimeter. Although this condition of added complication could be wholly or at least partially remedied by pregaging and classification grouping of workpieces, any such means have heretofore proven to be uneconornical. From the foregoing, it follows that in order to accomplish the above-stated results the centers of successive workpieces always must be located at the predefined position irrespective of random diametrical variations between the consecutive workpieces.

In the co-pending application of Roald Cann, filed April- 1, 1957, Serial No. 649,765, there is disclosed a device which includes self-containing sensing means for automatically adjusting the relatively position of the radial supporting shoes to compensate for differences of outside diameters between successive workpieces. This invention relates to certain additional improvements which would make the Cann compensating radial'work support more versatile.

It is therefore an object and purpose of this invention to provide an improved apparatus for accepting at random workpieces having different outside diameters and supporting them for internal centerless grinding so that the centers of the different outside diameter workpieces are located on a single definite line normal to the line of relative feed motion between the work and the tool.

For a complete understanding of this invention, reference may be had to the following detailed description taken in connection with the accompanping drawings, wherein:

Figure 1 is a side elevation with a portion in section, illustrating a preferred embodiment;

'Figure 2 is a side elevation illustrating a variation of the embodiment of Figure l;

[Figure 3 is a sectional view taken along line 33 of Figure 2. I

Referring to Figure 1, 10 indicates-the surface of a grinding machine bed whereon a bracket 12 is supported, forming part of a headstock assembly which includes a rotatable work-driving spindle. A driver face 18 on the headstock spindle normal to its axis supports the workpiece axially in frictional relationship and drives the workpiece in a manner as described in the Arms et a1. patent, 2,63 5,395, referred to above.

A rotatable spindle 20 carries a tool T and is shown as located within the inner periphery of an annular work- .piece W. The machine is arranged for transverse feed movement between the workpiece and the tool along a line of feed F running from the center of spindle 20 to a center 0 of a workpiece of median outer diameter when radially supported with the center in a predetermined position ona line normal to the feed line by means which will be described forthwith. The tool is adapted to be presented to the inner surface of the annular workpiece for the purpose of generating an accurate inner diameter. A member 22 consists of a fixed portion 21 rigidly attached to a face plane of the bracket 12 by screws 25, and a movable portion 23. A shoe 16 is nested in the fixed portion 21 and another shoe 24 is nested in movable portion 23 angularly spaced from shoe 16. The movable portion 23 containing shoe 24 is hinged to portion 21 by a weakened portion 28. This hinge permits a limited degree of rocking movement about its pivotal axis only. Flexible reeds ,or other types of hinges could, of course, be utilized instead of the weakened portion hinge 28. With this hinge arrangement, movable portion 23, which contains the shoe 24, may pivot about the pivotal axis of hinge 28'. This pivotal axis or pivot point is located on an imaginary line P which is parallel with an imaginary line N normal to the line of feed through the center of the workpieces. The distance A from the pivot point to line F along line P is half the distance 2A between lines N and P. Also located on line P is the fulcrum of a bar 40, which is indicated as a knife-edge bearing 42.

On the line N diametrically opposite the shoe 16 is another shoe 26 which is a sensing element. This shoe 26 is nested in one end of an adder bar 40 which is arranged with a fulcrum at a knife edge bearing 42 located on line P a distance 2A from line N. The adder bar 40 carries an adjustable button 44 on the end opposite shoe 26 and equidistant from the fulcrum, that is, both button 44 and shoe 16 are a distance 2A from line P on opposite sides thereof. The adjustable button 44 is adaptedto cooperate with an anvil 46 on the rockable member 23.

A fluid-power cylinder 50 is attached to the bracket 12 and may be supplied with pressurized fluid through a conduit 52 from a suitable source, not shown. A piston 54 is contained within the cylinder and, when pressurized fluid is supplied to the cylinder behind the piston it is displaced until seated against a shoulder 55 in the bottom of the cylinder. A piston rod 56 terminating in a knife edge cooperates with the bearing 42 to form the fulcrum of the bar 40 along line P. When the fluid pressure is removed, a pair of springs 58-58 will displace the bar 40 away from the position established by the shoulder 55.

A compression spring 34 is interposed between a lug 32 on bracket 12 and movable support portion 23 to urge this'portion to pivot counter-clockwise about pivot point or hinge 28 and thereby bias shoe 24 against the outer periphery of the workpiece W. To adjustably and selectively limit the amount of rocking movement, a pin 35 is attached to member 23 and the outer portion of this pin is threaded at 36 to accommodate nuts 38 which may be adjusted to determine the extent of the rocking movement. V

A locking arrangement is provided for a rockable member 23. This device consists of a carrier 60 rigidly attached to bracket 12 by means of screws 61 and hav- Pa te ntd June 17, 1958 ing a locking device 62 for the purpose of locking member 23 in its adjusted position against the face plane of bracket 12.

Initially, the compensatingv radial work support is preferably adjusted in the following manner: A workpiece of median outside diameter is seated against shoes 16 and 24 and piston 54 is forced by the fiuid pressure to the position shown, seated against shoulder 55, thereby placing the sensing element 26 in contact with the outer periphery of the workpiece W. Stop 44 is then adjusted in contact with anvil 46 until an imaginary line connecting the points of contact between stop 44 and anvil 46 and the shoe 26 and the workpiece is substantially normal to line Pand parallel to line F. The adjusting nuts 38 are adjusted to limit the rocking movement of portion 23 so that with no workpiece present, shoe 24 will be positioned a minute amount closer to center than the radius of the smallest diameter workpiece permissible.

In operation, if a workpiece larger than the'median outside diameter is introduced, the sensing element 26 will be displaced away from shoe 16 an amount equal to the additional diameter, thus rocking the arm 40 about pivot 42 and moving stop 44 in an opposite direction and thereby causing portion 23 to translate same amount at the point of contact on anvil 46. Due to the particular location of the pivot point 23, the amount of translation at the point of contact between shoe 24 and the workpiece is halved, corresponding to the additional radius size. In other words, sensing element 26 diametrically opposite from fixed shoe 16 senses the outside diameter of the workpiece and translates this diameter into a radius adjustment of shoe 24. If a workpiece of smaller diameter than the median size is introduced, the changes would occur in an opposite sense. From the foregoing, it may be seen that, within reasonable limits, any sized workpiece when placed in the compensating work support will always be positioned with the center of its supported outside diameter on the line N.

When the workpiece has been positioned in the support and the shoe 24 has been automatically located to compensate for the outer diameter of the workpiece, the locking means 62 are operated to fix the position of shoe 24-. Then the fluid pressure may be relieved in conduit 52, permitting springs 58 to lift the bar 40, thereby removing sensing element 26 from contact with the workpiece. The machine is then in condition to commence the grinding operation.

Figure 2 illustrates a modification of the invention. In this modification, the sensing element is diametrically opposite the movable support shoe instead of being diametrically opposite the fixed support shoe. This requires a different arrangement of the geometry of the parts involved to position a movable shoe in accordance with the different outside diameters of successive workpieces. A bracket 112, which is fixed to the bed of the grinding machine, supports a member 122 which has a portion 121 fixed to the bracket by means of screws 12:7. A fixed radial support shoe 116 is nested in the fixed support portion 121 to support a workpiece of median outside diameter with its center on the line of feed F with the line N normal thereto at the point of the fixed support. A movable portion 123 of memher 122 is hinged to portion 121 by a suitable hinge such as weakened portion 123 in a manner similar to that described in connection with Figure 1. A shoe 124 is fixedly nested in movable portion 123 to support a workpiece of median size outside diameter where line F intersects a line between this point of support and the hinge or pivot point at 128, which latter line is preferably parallel to line N. Portion 123 also carries an 'anvil 146 located on a line P parallel to the line F. This anvil and the pivot point 128 are the same distance, 2A, from line F on opposite sides thereof. A carrier which is rigidly secured to the bracket 112 by screws 161 carries a locking device 162 for accomplishing a locking function in a similar manner to that described in conjunction with Figure l.

A cambered pin 156 is fixedly secured to bracket 112 at a position located on line P which is parallel to line F a distance A therefrom. A sensing element 126 is attached to a bar 140 which is secured to acarrier 170. The carrier is pivotally supported at 172 on a lug 174 integral with bracket 112 and may be swingably positioned as indicated in broken lines if it is desired to have radial workpiece loading. A forkshaped portion of the carrier 170 is provided with a generally V- formed bearing means 171 which pivotally support journal portions of a semicircular pin 142 attached to the bar 140, and this pin has a plane through the center thereof in contact with pin 156 to form the fulcrum for the bar 140. A sensing element 126 carried by one end of the arm a distance A from the fulcrum contacts the outer periphery of a median size workpiece on line F diametrically opposite shoe 124. The arm 140 carries a contact button 144 on the end opposite sensing element 126 equidistant from the fulcrum, and this button 144 is adapted to contact the anvil 146. 7

Due to the location of the various contact points, fulcrums, pivot point and sensing element, the kinematics of the mechanism and the described system will give the same results as that described in connection with Figure 1. That is, when the distances from the fulcrum of arm 140 to shoe 126 and button 144 are equal and the distance between the line F and the pivot point 128 is twice this distance, the sensing element 126 will sense the outside diameter of the workpiece and translate this change in outside diameter into a movement of shoe 124, which movement will be one-half of the change in outside diameter.

For the purposes of illustration only, applicant has disclosed two embodiments of an improved compensating radial work support for an internal centerless grinding machine. These illustrated embodiments are not limiting as the invention is limited only by the scope of the appended claims.

I claim:

1. In an internal grinding machine, having a rotatable work driver, a tool adapted to be positioned in working relationship to the interior of an annular workpiece on which an internal surface .is to be generated concentric with a performed external surface, means to impart a relative transverse movement between the axes of said tool and work driver along a line of feed; a radial work support comprising: first and second shoes radially supporting a workpiece on said performed external surface and in frictional relationhip thereto, the first shoe being a single-line support and supporting the workpiece on a line parallel to said line of feed and being rigidly mounted in relation to the work driver, the second shoe supporting the workpiece with a wall of the workpiece interposed in the space between the shoe and the tool in the path of said transverse movement, a movable member carrying the second shoe; a separate third shoe used as a sensing element contacting the preformed external surface of the workpiece when in grinding position, said third shoe located opposite one of said other two shoes to sense the diameter of the workpiece; and a separate movable member carrying said third shoe and cooperating with said movable member carrying the second shoe to position said second shoe carrying member to compensate for random differences between the outer diameter of successive workpieces. I

2. A device as defined in claim 1 and further compris- 'ing locking means to lock said member in its compensated adjusted position and wherein said movable member is rockableabout a pivot.

3. A device as defined in claim 2 wherein spring means are provided to consistently urge said rockable member in a direction to displace 5: id second shoe toward the position of said tool whilst in working relationship; and means to adjustably limit the amount of displacement.

4. A device as defined in claim 3 wherein said sensing element is diametrically opposite said first shoe on a line normal to said line of feed; and further comprising: a bar pivotally supported on a line running through said pivot point of said rockable member and normal to said line of feed, said bar carrying said sensing element and being provided with an adjustable stop element adapted to cooperate with a portion of said rockable member, said stop element and said portion located on the side of the normal line on which said pivots are located opposite the 15 2,646,652

sensing element and equidistant therefrom.

5. A device as defined in claim 4- further comprising means to definitely locate the fulcrum of the bar at a predetermined point on the normal line through the fulcrum, and means consistently urging the bar away from said line of feed.

6. A device as defined in claim 3 wherein said third shoe used as a sensing element is located opposite said second shoe and wherein said third shoe movable carrying member is pivotally mounted on another hinged support for moving said third shoe sensing element into and out of diameter sensing position.

References Cited in the file of this patent UNITED STATES PATENTS Blood July 28, 1953 2,758,427 Quimby Aug. 14, 1956

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