Belt grinding assembly having pivoting means

Abstract

 The belt grinding assembly (10) according to the present invention includes (a) a frame (b) a belt grinding mechanism comprising a continuous abrasive belt (17) having a backing with front and rear surfaces, and abrasive granules attached along the front surface; a mechanism for driving the abrasive belt in a first direction along a path relative to the frame; (c) a backup (22) having a support surface (23) for the belt along the path; which support surface is straight in the first direction and has a uniform shape corresponding to the shape of the edge surface in a direction at a right angle to the first direction; (d) a wheel (28) having a periphery (27), a wheel axis (26) at a right angle to the first direction; a mechanism mounting the wheel on the frame for rotation about the wheel axis; drive mechanism (69,70) for rotating the periphery of the wheel past a loading station (33) relative to the frame, and then past the support surface (23) at a uniform rate of speed and in a first rotational direction; and (e) a plurality of pivoting object holder assemblies (100) including an engagement mechanism for releasably engaging and holding an object (12) along the radially outward side.

Description

Technical Field

[0001] The present invention relates to belt grinding assemblies adapted for use in grinding a smooth arc on an edge surface extending between major side surfaces on an elongate bar or object such as a wrench, which edge surface has a predetermined shape that may not be linear along the length of the bar or wrench.

Background of the Invention

[0002] Belt grinding assemblies are known that are adapted for use to grind a smooth arc on an edge surface extending between major side surfaces on an object or elongate bar such as a wrench, which edge surface has a predetermined shape when viewed in the planes of the major surfaces that may or may not be linear along the length of the wrench. Such grinding assemblies are useful to change an original rough or irregular edge surface resulting from the method by which the wrench was formed (e.g., drop forging) into a smoothly arced edge surface that is more aesthetically pleasing and easier on the hand of user of the wrench than the original rough or irregular edge surface. One such grinding assembly comprises the combination of (1) a belt grinding assembly including a drive mechanism for driving an abrasive belt in a first direction along a path past a backup platen fixed to frame means for the assembly, which platen has a support surface for the abrasive belt adjacent its rear surface that is straight in direction of travel of the belt and has a uniform shape corresponding to the shape of the edge surface to be radiused in a direction at a right angle to the direction of travel of the belt; and (2) bar manipulating means for moving the edge surface of the bar along an arcuate path about an axis at a right angle to the direction of travel of the belt into forceful engagement with the abrasive coated surface of the belt along the support surface to form the radius on the bar.

[0003] In this known belt grinding assembly the bar manipulating means is provided by a conveyer including a conveyer belt formed by two parallel spaced endless lengths of roller chain, metal slats extending transversely between opposite chain links, and receptacles for the bars attached to the slats on the sides of the slats opposite the lengths of chain; and a drive mechanism for the belt including two parallel spaced axles each carrying two axially spaced sprockets around which the chains were tensioned. Each of the receptacles is adapted to receive one of the bars therein with the length of the bar extending parallel to the slats and an edge surface of the bar projecting away from the slats, and the sprockets at one end of the conveyer are positioned so that movement of one of the receptacles around the sprockets on one of the axles will move a bar in the receptacle in an arc into forceful engagement with the abrasive belt along the support surface to grind a radius on the edge surface of the bar.

[0004] Another such grinding assembly comprises the combination of (1) a belt grinding assembly including a drive mechanism for driving an abrasive belt in a first direction along a path past a grinding station; and (2) bar manipulating means for moving the edge surface of the bar along an arcuate path about an axis at a right angle to the direction of travel of the belt into forceful engagement with the abrasive coated surface of the belt at the grinding station to form the radius on the bar; the bar manipulating means being provided by a drum having receptacles for the bars attached to its periphery; and a chain drive mechanism for the drum. Each of the receptacles is adapted to receive one of the bars therein with the length of the bar extending parallel to the axis of the drum and an edge surface of the bar projecting away from the slats, and the drum is positioned so that movement of one of the receptacles around its periphery will move a bar in the receptacle in an arc into forceful engagement with the abrasive belt along the support surface to grind a radius on the edge surface of the bar.

[0005] While such a grinding assemblies can grind a radius on the side surface of a bar or wrench, they present several problems. Looseness of the bar in the holder, between the conveyer belt and the sprockets, or in the chain drive allows the bar to momentarily not be moved by the drive mechanism as the bar is initially brought into engagement with the abrasive belt along the support surface, after which the drive mechanism does move the bar into forceful engagement with the abrasive belt until the bar is positioned along the support surface so that the force of such engagement is directed to move the bar with the belt, whereupon such looseness allows the bar to move with the belt, resulting in movement of the bar too quickly out of engagement with the abrasive belt along the support surface. The result of such engagement between the bar and the belt is to produce a ground edge surface on the bar that is not uniform in that too much metal is removed from the portion of the bar that initially engages the belt, and too little metal is removed from the portion of the bar that is in final engagement with the belt. Also, the bar or wrench can fall free of the holders as it moves out of engagement with the belt, which can be dangerous.

[0006] A problem associated with the grinding assemblies described in U.S. application serial number 07/359,729, filed May 31, 1989 or EPO Patent Application 0400901 is that such grinding assemblies tend to have difficulty in grinding small arcs (e.g. less than 1.0 inch radius on 0.25 inch thick edges of wrenches) on objects. For such a grinding assembly, the wheel should have a sufficiently large radius so that a number of tool receptacles may be placed on the periphery of the wheel. Generally, the larger the radius of the wheel, the greater the number of tool receptacles may be placed on the periphery of the wheel and the slower the speed of the periphery of the wheel per the number of objects ground. However, as the radius of the wheel increases, the arc in which the receptacles move the workpieces into forceful engagement with the abrasive belt along the support surface becomes "flatter" (i.e. the radius of curvature decreases). The resultant radius ground on the object is relatively large and thus, such devices tend to grind an undesirably large radius on the edge surface of the wrench or workpiece which results in a wrench with an insufficiently smooth edge which may be rough on the hands of a user and less aesthetically pleasing.

Disclosure of Invention

[0007] The present invention provides a belt grinding assembly that can grind a relatively small, uniformly arced edge surface (e.g. a 0.25 inch radius on a 0.25 inch thick edge of a wrench) extending between major side surfaces on an elongate bar such as a wrench, which edge surface has a predetermined shape that may or may not be linear along the length of the bar or wrench.

[0008] The belt grinding assembly according to the present invention includes (1) frame means; (2) a belt grinding mechanism comprising a continuous abrasive belt having a backing with front and rear surfaces, and abrasive granules attached along the front surface; means for driving the abrasive belt in a first direction along a path relative to the frame; (3) a backup having a support surface for the belt along the path; which support surface is straight in the first direction and has a uniform shape corresponding to the shape of the edge surface in a direction at a right angle to the first direction; (4) a wheel having a periphery, a wheel axis at a right angle to the first direction, and a wheel radius defined from the wheel axis; means mounting the wheel on the frame means for rotation about the wheel axis; drive means for rotating the periphery of the wheel past a loading station relative to the frame means, and then past the support surface at a generally uniform rate of speed and in a first rotational direction; and (5) a plurality of object holder assemblies having radially outward and inward sides, each object holder assembly including engagement means for releasably engaging and holding an object along the radially outward side.

[0009] The object holder assemblies each include pivotal mounting means mechanisms for mounting the object holder assemblies about object holder assembly axes that are parallel to the axis of the wheel and which are spaced about the periphery of the wheel. The pivotal mounting mechanisms mount each of the object holder assemblies with the engagement means projecting radially outwardly of the wheel for pivotal movement about the object holder axis between pre-grinding and post-grinding positions with pivotal movement of the object holder assembly from the pre-grinding to the post-grinding position being generally in the first rotational direction of the wheel.

[0010] The grinding assembly may include a biasing means for biasing each object holder assembly toward the pre-grinding position in the form of a plurality of springs each having a pair of ends, with one end of each of the coil springs attached to a position on the wheel generally adjacent the wheel axis and with the other end of the coil springs being attached to the radially inward side of an object holder assembly.

[0011] The grinding assembly includes pivoting cam means mounted on the frame generally adjacent the support surface for pivoting each object holder assembly from the pre-grinding position to the post-grinding position against the bias of the biasing means (springs) during movement of the object holder assembly past the back-up means to bring an object into forceful engagement with the abrasive belt along the support surface so that a radius smaller than the radius of the wheel may be ground on the object. The pivoting cam means preferably comprises a cam bar fixedly mounted on the frame and adapted to engage the pivotal mounting means.

[0012] Preferably, movement of the edge surface of the object along an arcuate path into forceful engagement with the abrasive belt at a generally uniform rate of speed is facilitated by the drive means comprising a helical gear coaxial with the wheel and having a diameter dimension of within 25 centimeters (10 inches) of the diameter dimension of the wheel, a driving worm gear having an axis at a right angle to the axis of the helical gear and engaged with the helical gear, means for mounting the worm gear for radial movement relative to the helical gear, and means for biasing the teeth of the worm gear into engagement with the teeth of the helical gear to restrict backlash between the gears.

[0013] Also preferably, each of the engagement means comprise a first jaw, and means for releasably attaching the first jaw to the radially outward side of the object holder assembly in a position fixed relative to the object holder assembly. The means for releasably attaching the first jaw to the radially outward side of the object holder assembly may comprise structural means on the radially outward side of each of the object holder assemblies defining a slot extending generally parallel to the wheel axis and having an inlet opening at one end. The first jaw has a base adapted for close fitting engagement in the slot, and means for releasably retaining the base in the slot. The slot is defined by a part of the peripheral surface of the object holder assembly and at least one side surface disposed at an acute angle relative to the periphery of the object holder assemblies. There may also be means for releasably retaining the base in the slot in the form of means for forcefully pressing the base against the side or bearing surface of the slot.

[0014] The engagement means also preferably comprise a second jaw, and jaw actuation means for mounting the second jaw on the object holder assembly for movement relative to the first jaw between a release position with the second jaw spaced freely from the first jaw to receive the object between the jaws, and an engage position adapted to firmly clamp the object between the jaws. The jaw actuating means preferably includes springs mounted on each of the object holder assemblies between the jaws for biasing the second jaw toward the engage position, and cam means including a jaw cam follower connected to the second jaw.

[0015] The belt grinding assembly may include release and loading cams mounted on the frame means and axially offset from the cam bar. The release and loading cams have cam surfaces positioned for engagement by the jaw cam follower to move the second jaw to the release position against the bias of the spring biasing the second jaw toward the engage position.

[0016] Each of the plurality of object holder assemblies preferably include leveling means comprising a leveling cam follower mounted on the radially inward side of the object holder assembly. The release and loading cams mounted on the frame means have surfaces positioned for engagement by the leveling cam follower to fix the object holder assembly relative to the wheel. As stated above, the release and loading cam surfaces are also positioned for engagement by the jaw cam follower to move the second jaw to the release position and to level the object holder assembly in a leveled position.

Brief Description of Drawing

[0017] The present invention will be further described with reference to the accompanying drawing wherein like reference numerals refer to like parts in the several views, and wherein:

Figure 1 is a fragmentary front vertical view of a belt grinding assembly according to the present invention, which view has parts broken away to show details;

Figure 2 is a fragmentary side vertical view of a belt grinding assembly according to the present invention;

Figure 3 is a perspective view of a wheel according to the present invention with portions omitted to show detail;

Figure 4 is an enlarged fragmentary side vertical view of a belt grinding assembly according to the present invention, taken approximately along lines 4-4 of Figure 1, which view has parts broken away to show details;

Figures 5 through 8 are enlarged fragmentary side vertical views of a belt grinding assembly according to the present invention, which views have parts broken away to show details and which sequentially illustrate an object holder assembly being moved between the pre-grinding and the post-grinding positions;

Figure 9 is an enlarged perspective view of portions of an object holder assembly according to the present invention; and

Figure 10 is an enlarged fragmentary sectional view taken approximately along lines 10-10 of Figure 4.

Detailed Description

[0018] Referring now to the drawing, there is shown a belt grinding assembly 10 adapted for use on an elongate bar such as a wrench 12 illustrated having opposite major side surfaces and an initial edge surface 14 between the side surfaces that is rough and has a predetermined shape when viewed in the planes of the major surfaces that may not be linear along the length of the wrench 12. The grinding assembly 10 is adapted to grind a relatively small, uniformly arced edge surface (e.g. a 0.25 inch radius on a 0.25 inch thick edge of a wrench) extending between major side surfaces on the wrench 12 to form a new edge surface extending between the side surfaces that is smoothly arced while retaining the predetermined shape along the length of the wrench 12.

[0019] Generally the belt grinding assembly 10 comprises frame means; (2) machining means such as a belt grinding mechanism comprising a belt driving mechanism 16 comprising a conventional continuous abrasive belt 17 having a flexible cloth backing with front and rear surfaces 18 and 19, and abrasive granules attached along its front surface 18 (e.g., the abrasive belt sold by Minnesota Mining and Manufacturing Company, St. Paul, Minnesota, under the trade designation 3M 331D "Three-M-ite" T.M. Resin Bond Cloth Belts), means for driving the abrasive belt 17 in a first direction along a path relative to frame means for the assembly 10 in the form of a conventional belt drive mechanism (not shown) including spaced rollers around which the abrasive belt 17 is tensioned and a motor drive assembly that drives the rollers and thereby the abrasive belt 17 (e.g. the vertical slack belt machines sold by KLK Industries, Crystal, Minnesota, or G & P Industries, Indianapolis, Indiana); a backup platen 22 fixed to the frame means and having a support surface 23 along the path adjacent the rear surface 19 of the abrasive belt 17, which support surface 23 is straight in the first direction in which the abrasive belt 17 is driven (see figures 2 and 4) and has a uniform shape corresponding to the shape of the edge surface 14 in a direction at a right angle to the first direction in which the abrasive belt 17 is driven (see figure 10); and workpiece feed means for moving the edge surface 14 of the wrench 12 at a generally uniform rate of speed along an arcuate path about axes 26 and 101 which are at right angles to the first direction in which the abrasive belt 17 is driven into forceful engagement with the abrasive belt 17 along the support surface 23.

[0020] The workpiece feed means or mechanism preferably comprises a wheel 28 having axis 26, a generally cylindrical periphery 27; means in the form of an axle 29 for the wheel 28 journaled in bearings 30 on the frame means. The axle 29 mounts the wheel 28 on the frame means for rotation about the axis 26 at a right angle to the first direction in which the abrasive belt 17 is driven to sequentially move the periphery 27 of the wheel 28 past a loading station 33 relative to the frame means, and then past the support surface 23 of the platen 22. There is also present drive means for rotating the periphery 27 of the wheel 28 past the support surface 23 of the platen 22 at a uniform rate of rotation.

[0021] The belt grinding assembly 10 includes a plurality of object holder assemblies 100 (Figures 4 through 8) having radially outward and inward sides, each object holder assembly 100 including engagement means for releasably engaging and holding a wrench 12 along its radially outward side.

[0022] Each of the object holder assemblies 100 include pivotal mounting means or mechanisms for mounting the object holder assemblies about object holder assembly axes 101 that are generally parallel to the axis 26 of the wheel 28 and which are spaced about the periphery of the wheel 28. The pivotal mounting means preferably comprises a cylindrical axle 140 positioned within and coaxial with a cylindrical bushing 142 mounted in a cylindrical bore 141 in the object holder assembly 100. The pivotal mounting mechanisms mount each of the object holder assemblies 100 with the engagement means projecting radially outward of the wheel 28 for pivotal movement about the object holder axes 101 between pre-grinding (Figure 5) and post-grinding (Figure 7) positions relative to the wheel 28. The pivotal movement of the object holder assembly 100 from the pre-grinding to the post-grinding position is generally in the first rotational direction of the wheel 28.

[0023] The pivotal mounting means also preferably comprises generally V-shaped cam followers 150 mounted on inner portions of each of the object holder assemblies 100 (Figure 9). The V-shaped cam followers 150 have leading 151 and trailing 152 portions which have surfaces adapted to engage pivoting cam means (to be explained later) to pivot the object holder assembly 100 from the pre-grinding to the post-grinding position to thereby bring the wrench 12 into forceful engagement with the abrasive belt 17 along the support surface 23.

[0024] Optionally, the grinding assembly 10 may include a biasing means for biasing each object holder assembly 100 toward the pre-grinding position in the form of springs 104 each having a pair of ends, with one end of each of the coil springs 104 attached to a position on the wheel 28 generally adjacent the wheel axis 26 and with the other end of the coil springs 104 being attached to the radially inward side of an object holder assembly 100 by means of, for example, an eyelet 109.

[0025] Additionally, the grinding assembly 10 includes pivoting cam means attached to the frame means generally adjacent the support surface 23 for pivoting each object holder assembly 100 from the pre-grinding position to the post-grinding position against the bias of the biasing means (springs 104) during movement of the object holder assembly 100 past the back-up platen 22 to bring an object such as wrench 12 into forceful engagement with the abrasive belt 17 along the support surface 23 so that a radius smaller than the radius of the wheel 28 may be ground on the wrench 12. The pivoting cam means preferably comprises a cam bar 160 fixedly mounted on the frame means and adapted to engage the leading and trailing surfaces 151 and 152 of the V-shaped cam follower 150 of the pivotal mounting means.

[0026] The leading surface 151 of the V-shaped cam follower 150 is preferably arcuate and is adapted to engage cam bar 160 as the object holder assembly 100 moves past the backup platen 22. Engagement between the cam bar 160 and the leading 151 and trailing 152 surfaces of V-shaped cam follower 150 causes the object holder assembly 100 to pivot about axis 101 as the assembly 100 moves past the backup platen 22. Pivoting the object holder assembly 100 at this location affords grinding a smaller radius along the edge of the wrench 12 than would be ground without the pivoting of the object holder assembly 100.

[0027] As best seen in Figure 8, after the V-shaped cam follower 150 moves past the cam bar 160, the spring 104 urges the object holder assembly 100 back into a pre-grinding position relative to the periphery of the wheel 28. A 1.5 inch thickness T of the cam bar 160 ensures that the spring 104 does not cause the object holder 100 to pivot the wrench 12 back into engagement with the belt 17 after the edge of the wrench 12 has been ground. Also, supplying the trailing portion 152 to the V-shaped cam follower 150 ensures that the wrench 12 will slowly and smoothly move toward the pre-grinding position from the post grinding position and thus prevents the wrench 12 from being thrown from the engagement means (e.g. jaws 35 and 36).

[0028] First and second spaced jaws 35 and 36 are mounted on the wheel 28 in spaced relationship about its periphery 27. The engagement means comprises the first jaw 35, means for releasably attaching the first jaw 35 to the radially outward side of the object holder assembly 100 in a position fixed relative to the object holder assembly 100; the second jaw 36, and jaw actuation means (later to be explained) for mounting the second jaw 36 on the object holder assembly 100 for movement relative to the first jaw 35 between a release position (see the jaws 35 and 36 at the loading station 33) with the jaws 35 and 36 spaced to freely receive a wrench 12 between the jaws 35 and 36, and an engage position (see the jaws adjacent the platen 22) adapted to firmly clamp the wrench 12 between the jaws 35 and 36, and means for positioning the jaws 35 and 36 in their engage position as each object holder assembly 100 moves past the support surface 23 of the platen 22.

[0029] For each pair of jaws 35 and 36, the first jaw 35 is releasably attached to the radially outer surface of the object holder assembly 100 in a fixed position relative to the object holder assembly 100 by means later to be explained. The second jaw 36 is mounted on the object holder assembly 100 by means including a pivot pin 40 (Figure 6) for pivotal movement relative to the object holder assembly 100 between the release and the engage positions.

[0030] The jaw actuating means includes a spring 42 (Figures 4 and 10) between the first jaw 35 and the second jaw 36 for biasing the second jaw 36 toward the engage position of the jaws 35 and 36, and cam means including a cylindrical jaw cam follower 43 mounted on the second jaw 36 for rotation about an axis parallel to the axis 26 of the wheel 28, and first (e.g. a loading) and second (e.g. release) cams 45 and 46 mounted on the frame means. The cams 45 and 46 have cam surfaces positioned for engagement by the jaw cam followers 43 to position the second jaws 36 in the release positions of the jaws 35 and 36 when the pairs of jaws 35 and 36 are at the loading station 33 preceding the platen 22 or at an unloading station 48 subsequent to the platen 22 and fixed relative to the frame means along the lowermost portion of the wheel 28. The pairs of jaws 35 and 36 are moved from the release position at the loading station 33 to the engaged position. In the engaged position, the jaws 35 and 36 are moved past the support surface 23 of the platen 22 and then to unloading station 48 where they are again moved to the release position and the finished wrench 12 is dropped into a receptacle (not shown).

[0031] As can best be seen in figures 6 and 10, each pair of jaws 35 and 36 is shaped to position the wrench 12 at a predetermined position there between, such as through the use of a pin 49 received between jaws of the wrench 12 and a pin 50 for supporting the edge surface of the wrench 12 opposite the edge surface 14 being radiused by the belt 17. Different shaped jaws 35 and 36 may thus be required for different shaped wrenches, and the use of such different shaped jaws is facilitated by the means for releasably attaching the first jaw 35 described below, and means for changing a minor contact portion 52 of the second jaw 36 that is shaped to engage a particular wrench or other bar. That means for changing the contact portion 52 of the movable jaw 36, best seen in figures 4 and 6, comprises the second jaw 36 having a major portion 53 pivotably mounted on the pivot pin 40 and on which major portion 53 the jaw cam follower 43 is mounted, which major portion 53 has a pivotable support pin 54 projecting generally centrally and radially of the wheel 28, on which pivotable support pin 54 the minor contact portion 52 of the second jaw 36 is pivotably mounted. Pivotal movement of the minor contact portion 52 of the second jaw 36 around the pin 54 insures complete contact of the second jaw 36 with the wrench 12 between the jaws 35 and 36. The minor contact portion 52 of the second jaw 36 is retained in place on the pin 54 and against the major portion 53 by a leaf spring 56 having an end portion fixed on the major portion 53 of the second jaw 36, and carrying a lug 57 on its distal end adapted to engage over a lip on the minor contact portion 52 of the second jaw 36. When desired, the contact portion 52 can be easily replaced by a contact portion of a different shape by pulling the lug 57 out of the recess in the contact portion 52 of the second jaw 36 against the bias of the leaf spring 56, lifting the contact portion 52 off of the pin 54, positioning the new contact portion on the pin 54, and allowing the lug 57 to enter the recess in the new contact portion under the influence of the leaf spring 56 to retain it in place.

[0032] Each of the plurality of object holder assemblies preferably include leveling means comprising a leveling cam follower 166 mounted on the radially inward side of the object holder assembly 100. Release 46 and loading 45 cams mounted on the frame means have surfaces positioned for engagement by the leveling cam follower 166 to fix the object holder assembly 100 relative to the wheel 28 at the loading and unloading stations 33 and 48. The release and loading cam surfaces 45 and 48 are also positioned for engagement by the jaw cam follower 43 to move the second jaw 36 to the release position and to level the object holder assembly in a leveled position relative to the wheel 28 generally midway between the pre-grinding and the post-grinding positions (see Figure 4) against the bias of the springs 104 at the loading and unloading stations 33 and 48. The leveling cam follower 166 and jaw cam follower 43 are axially offset (relative to the wheel axis 26) from the V-shaped cam follower 150 so that they do not engage the cam bar 160 when the object holder assembly 100 moves past the support surface 22. Placing the object holder assemblies 100 in the leveled position at the loading station 33 provides a convenient orientation for a user to place an unground wrench 12 between jaws 35 and 36. Placing the object holder assemblies 100 in the leveled position at the unloading station 48 affords a controlled, precise drop of a ground wrench 12 into a tool receptacle (not shown) positioned in a predetermined location relative to the wheel 28.

[0033] The portion of the engagement means comprising means for releasably attaching the first jaw 35 to the radially outward side of the object holder assembly 100 may comprise structural means on the radially outward side of each of the object holder assemblies 100 defining a slot 61 extending generally parallel to the wheel axis 26 and having an inlet opening at one end. The first jaw 35 has a base 62 adapted for close fitting engagement in the slot 61, and means for releasably retaining the base 62 in the slot 61. The radially outward side of each of the object holder assemblies 100 has a peripheral surface. The slot 61 is defined by a part of the peripheral surface and at least one side side or bearing surface 95 disposed at an acute angle relative to the periphery of the object holder assembly 100. Preferably the slot 61 comprises a dovetail slot but may comprise a slot having only one side disposed an acute angle relative to the outer surface of the object holder assembly 100. The means for releasably retaining the base 62 in the slot 61 may include means for forcefully pressing the base 62 against side or bearing surfaces 95 of the slot 61.

[0034] The slot surfaces 61 include bearing surfaces 95 diverging on opposite sides of the opening. The base or plate 62 has surfaces defining a socket opening through the bottom of the plate 62 and has shoulder surfaces 98 adapted to engage the bearing surfaces 95. The means for forcefully pressing the base 62 against the bearing surfaces 95 of the slot 61 includes detent means 76 having detent surfaces 77 adapted to engage the surfaces defining the socket in the plate 62 to position the plate 62 at a predetermined location relative to the object holder assembly 100. The detent means 76 are mounted on the object holder assembly 100 for movement between a locking position with the detent surfaces 77 of the detent means 76 engaged with the socket surfaces in the plate 62, and a release position with the detent surfaces 77 of the detent means disengaged from the socket to afford sliding movement of the plate 62 within the slot 61.

[0035] A coil spring 157 may bias the detent surfaces 77 of the detent means 76 toward the locking position. The spring 157 also biases the shoulder surfaces 98 of the plate 62 radially outward from the axis 26 toward engagement with the bearing surfaces 95 on the periphery of the slot 61 to provide secure frictional engagement between the shoulder surfaces 98 of the plate 62 and the bearing surfaces 95 of the slot 61 to thereby firmly hold the plate 62 within the slot 61 while the new surface is formed on the object or workpiece.

[0036] The coil spring 157 has two opposite ends with one end engaged with an L-shaped actuation member 21 and with the other end of the spring engaged with the object holder assembly 100. The L-shaped actuation member 21 is an element of an actuation means which is provided for moving the detent means 76 from the locking position to the release position against the bias of the spring 157 and for overcoming the secure frictional engagement between the shoulder surfaces 98 of the plate 62 and the bearing surfaces 95 of the slot 61 to thereby afford quick changing of the plate 62 and the first jaw 35 with a different plate and first jaw. The actuation means affords release of the bias from the spring 157 before the plate 62 is slid axially into or out of slot 61.

[0037] At its radially outer or upper end, the L-shaped actuating arm 21 includes surfaces defining a pair of apertures 32 which are adapted to receive a manual operable means (not shown) such as a fork shaped bar having two tangs projecting from a handle for moving the detent means 76 from the locking to the release position to afford changing of the plate 62 and the first jaw 35 with a different plate and first jaw.

[0038] The backup platen 22, which has a uniform shape corresponding to the shape of the edge surface 14 in a direction at a right angle to the first direction in which the abrasive belt 17 is driven, may be changed for different shaped wrenches or bars, and thus is removably attached to the frame means by bolts (not shown). The support surface 23 of the platen 22 along the path adjacent the rear surface of the abrasive belt 17 is covered with an about 1/8 inch thick layer of the graphite covered backing sold by Process Engineering Corporation, Crystal Lake, Illinois, which facilitates sliding movement of the backing of the abrasive belt 17 along the fixed support surface 23 when the wrench 12 is pressed into forceful grinding engagement with the abrasive belt 17 moving over it. There may be an elastic resiliently deflecting material (e.g. foam rubber) behind the fixed support surface 23 which is adapted to conform to the shape of the wrench 12.

[0039] The wheel 28 has a predetermined diametrical dimension (e.g., 76 centimeters or 30 inches) at its periphery 27, and the drive means for rotating the periphery 27 of the wheel 28 past the support surface 23 of the platen 22 at a uniform rate of rotation comprises a helical gear 68 coaxial with and fixed to the wheel 28 (which helical gear 68 has diametrical dimension of about 61 centimeters or 24 inches, which is, as is preferred, within 25 centimeters or 10 inches of the diametrical dimension of the wheel 28), a worm gear 69 having an axis at a right angle to the axis 26 of the helical gear 68 and wheel 28, which worm gear 69 is engaged with the helical gear 68 and is driven by a variable speed motor (not shown), means for mounting the worm gear 69 for radial movement relative to the helical gear 68, and means for biasing the teeth of the worm gear 69 into close fitting engagement with the teeth of the helical gear 68 to restrict backlash between the gears 68 and 69. The means for mounting the worm gear 69 for radial movement relative to the helical gear 68 and the means for biasing the teeth of the worm gear 69 into engagement with the teeth of the helical gear includes a portion 70 of the frame means on which the worm gear 69 is rotatably mounted, which frame means portion 70 includes a plurality of parallel pins 71 projecting at a right angle to the axis of the worm gear 69 and received for longitudinal sliding movement in sockets in a portion 72 of the frame means on which the wheel 28 is mounted, and coil springs 73 around the pins 71 between the frame portion 72 on which the wheel 28 is mounted and the frame portion 70 on which the worm gear 69 is mounted.

[0040] Means in the form of relatively movable portions of the frame means and adjustable mechanisms between those portions are also provided for providing precise alignment between the wrench 12 in the jaws 35 and 36 and the support surface 23 so that the wrench 12 will be brought into the desired engagement with the abrasive belt 17 along the support surface 23 to form the desired radius on the edge surface 14. The relatively movable portions of the frame means include (1) a fixed portion comprising a frame 81 of the belt driving mechanism 16, a floor 82 on which the frame 81 is mounted in a fixed position, and two parallel rail assemblies 83 supported in a fixed position on the floor 82; (2) a transversely movable portion 85 comprising a transversely movable plate 86 and four linear bearing assemblies 87 projecting from a bottom surface of the plate 86, which linear bearing assemblies 87 are mounted around the rail assemblies 83 for linear movement there along; a horizontally pivotable portion 88 comprising a horizontal pivot plate 89 laying in face to face contact with the upper surface of the transversely movable plate 86 and mounted by a bolt through the plates 86 and 89 for horizontal pivotal movement relative to the transversely movable plate 86 about a vertical pivot axis 90 closely adjacent to and generally centered on the abrasive belt 17; and the portion 72 which is vertically pivotable relative to the pivot plate 86 about a horizontal axis parallel to the axis 26 of the wheel 28 that is defined by pivot pins 92 through the vertically pivotable portion 72 and the horizontal pivot plate 89 on the sides thereof adjacent the abrasive belt 17.

[0041] An adjustment assembly 120 manually operable by a wheel 121 is mounted on the vertically pivotable portion 72 of the frame means and includes a screw jack portion including a threaded axially movable rod 122 having a lower end bearing against horizontal pivot plate 89 (e.g., the screw jack commercially designated a "Jaculator" T.M. available from Minnesota Bearing, St. Paul, Minnesota). Rotation of the wheel 121 changes the length of the portion of the rod 122 that extends between the vertically pivotable portion 72 and the horizontal pivot plate 89, thereby causing vertical pivotal movement of the vertically pivotable portion 72 relative to the horizontal pivot plate 89 about the pivot pins 92 and changing the engagement between the edge surface 14 of the wrench 12 and the abrasive belt 17 on the support surface 23 along the entire length of the wrench 12.

[0042] An adjustment screw assembly 105 is manually operable by a wheel 106 connected to a shaft rotatably mounted in a bearing block 108 mounted on the transversely movable plate 86 of the frame means, which shaft is coupled by a universal joint 129 to an extendible or retractable rod assembly 107 having an end attached to the horizontal pivot plate 89. Rotation of the wheel 106 provides means for changing the length of the rod assembly 122 (i.e., by screwing a threaded rod portion thereof into or out of an internally threaded socket portion thereof) thereby causing horizontal pivotal movement of the the horizontal pivot plate 89 and the wheel 28 carried thereby about the vertical pivot axis 90 on the top surface of the transversely movable plate 86 to adjust the engagement of one end of the wrench 12 relative to the other with the abrasive belt 17 along the support surface 23.

[0043] An adjustment screw assembly 110 is manually operable by a wheel 111 connected to a shaft rotatably mounted in a bearing block 113 mounted on a plate fixed to the floor 82 on which the rail assemblies 83 are fixed, which shaft is coupled by a universal joint 114 to an extendible or retractable rod assembly 112 having an end attached to the transversely movable plate 86 of the frame means. Rotation of the wheel 111 provides means for changing the length of the rod assembly 112 (i.e., by screwing a threaded rod portion thereof into or out of an internally threaded socket portion thereof), thereby causing horizontal movement of the transversely movable plate 86 and the wheel 28 it supports through the pivotal portion 88 to adjust the area of contact between the wrench 12 and the abrasive belt 17 along the platen 22 in a direction parallel to the axis 26 of the wheel 28.

[0044] The present invention has now been described with reference to one embodiment thereof. It will be apparent to those skilled in the art that many changes can be made in the embodiment described without departing from the scope of the present invention. For example, when the grinding assembly is used to radius a straight edge portion on a bar or wrench, the abrasive belt used need not have a flexible backing. Instead of the platen 22, the abrasive belt 17 could be backed by a wheel having a specially shaped or cylindrical periphery, depending on the shape of the bar or wrench to be radiused. The backup platen may be omitted altogether and the abrasive belt 17 may be driven as a "slack belt" with only belt tension for support. Additionally, the unloading station 48 could be located at any position between the platen 22 and the loading station 33, or the operator could remove the finished tool at the loading station 33 before placing a wrench to be finished between the jaws 35 and 36. The actuating means for moving the jaws 35 and 36 between their release and engage positions could be provided by air or hydraulic operated mechanisms or by mechanical mechanisms other than the spring and cam mechanism illustrated. The radius of the wheel 28 can be large (e.g., 30 inches) to form an edge surface with a large radius on the edge of a wrench or bar being finished, or can be made smaller (e.g. 10 inches) to form an edge surface with a smaller radius on the edge of a wrench or bar being finished. The portion 72 of the frame means on which the wheel 28 is journaled could be movably mounted on rails disposed at a right angle to the axis 26 of the wheel 28 between the pivot plate 86 and the portion 72 rather than being vertically pivotable relative to the pivot plate 86 about the pivot pins 92. The belt grinding mechanism 16 illustrated could be replaced by a contact wheel about which the abrasive belt is moved so that the contact wheel would provide the backup platen, and the belt grinding assembly thus modified could be used for grinding surfaces other than edge surfaces on bars, such as to grind the gates or other projections off of castings or other objects.

Claims

1. A belt grinding assembly adapted for use to form a new surface on an object, said grinding assembly comprising:
   frame means;
   a belt grinding mechanism comprising:
   a continuous abrasive belt having a backing with front and rear surfaces, and abrasive granules attached along said front surface;
   means for driving said abrasive belt in a first direction along a path relative to said frame means;
   backup means having a support surface for said belt along said path;
   a wheel having a periphery, a wheel axis at a right angle to said first direction, and a wheel radius defined from said wheel axis;
   means mounting said wheel on said frame means for rotation about said wheel axis;
   drive means for rotating the periphery of said wheel past said support surface at a uniform rate of speed and in a first rotational direction;
   a plurality of object holder assemblies having radially outward and inward sides, each object holder assembly including engagement means for releasably engaging and holding an object along said radially outward side, said object holder assemblies including:
   pivotal mounting means for mounting said object holder assemblies about object holder assembly axes that are parallel to the axis of the wheel and which are spaced about the periphery of said wheel;
   said pivotal mounting means mounting each of said object holder assemblies with said engagement means projecting radially outwardly of said wheel for pivotal movement about said object holder axis between a pre-grinding position and a post-grinding position with pivotal movement of said object holder assembly from said pre-grinding to said post-grinding position being generally in said first rotational direction of said wheel;
   biasing means for biasing each object holder assembly toward said pre-grinding position;
   pivoting cam means generally adjacent said support surface for pivoting each object holder assembly from said pre-grinding position to said post-grinding position against the bias of said biasing means during movement of the object holder assembly past said back-up means to bring an object into forceful engagement with the abrasive belt along said support surface so that a radius smaller than the radius of the wheel may be ground on the object.

2. A belt grinding assembly according to claim 1 wherein each of said engagement means comprises
   movable clamp means comprising first and second jaws with said first jaw spaced from said second jaw for relative movement between a release position with said second jaw spaced freely from said first jaw to receive the object between said jaws, and an engage position adapted to firmly clamp the object between said jaws; and
   jaw actuating means for moving said movable clamp means to the release position at a loading station comprising a release cam surface mounted on said frame means,
   a spring mounted between said jaws for positioning said jaws in said engage position during movement of said object holders past said support surface;
   said jaw actuating means moving each of said first and second jaws to said release position at said loading station, positions said jaws in said engage position as said clamp means moves past said support surface, and moves each of said first and second jaws to said release position at an unloading position fixed relative to said frame means along the lowermost portion of said wheel, and past which unloading position said pairs of jaws are moved after movement from said loading position past said support surface;
   wherein said drive means moves the object holder assemblies past said loading station relative to said frame means, then past said support surface, and then past said unloading station.

3. A belt grinding assembly according to claim 1 wherein
   said pivoting cam means comprises a cam bar mounted on said frame means and adapted to engage said pivotal mounting means, and
   each of said engagement means includes a first jaw, means for releasably attaching said first jaw to the radially outward side of said object holder assembly in a position fixed relative to said object holder assembly; a second jaw, and jaw actuation means for mounting said second jaw on said object holder assembly for movement relative to said first jaw between a release position with said second jaw spaced freely from said first jaw to receive the object between said jaws, and an engage position adapted to firmly clamp the object between said jaws;
   said jaw actuating means includes a spring between said jaws for biasing said second jaw toward said engage position, cam means including a jaw cam follower mounted on said second jaw; and
   release and loading cams mounted on said frame means and axially offset from said cam bar, said release and loading cams having cam surfaces positioned for engagement by said jaw cam follower to move said second jaw to said release position against the bias of said spring biasing said second jaw toward said engage position.

4. A belt grinding assembly according to claim 3 wherein each of said plurality of object holder assemblies includes leveling means comprising a leveling cam follower mounted on said radially inward side of said object holder assembly,
   said release and loading cams having surfaces positioned for engagement by said leveling cam follower to fix said object holder assembly relative to said wheel, and
   said release and loading cam surfaces also having surfaces positioned for engagement by said jaw cam follower to move said second jaw to said release position and to level said object holder assembly in a leveled position generally midway between said pre-grinding and said post-grinding positions against the bias of said biasing means for biasing each object holder assembly toward said pre-grinding position.

5. A belt grinding assembly according to claim 3 wherein said means for releasably attaching said first jaw to the radially outward side of said object holder assembly comprises structural means on the radially outward side of each of said object holder assemblies adapted for defining a slot extending generally parallel to said wheel axis and having an inlet opening at one end, said first jaw having a base adapted for close fitting engagement in said slot, and means for releasably retaining said base in said slot.

6. A belt grinding assembly according to claim 5 wherein said radially outward side of each of said object holder assemblies has a peripheral surface, said slot is defined by a part of said peripheral surface and at least one side surface disposed at an acute angle relative to the periphery of said object holder assemblies, and said means for releasably retaining includes means for forcefully pressing said base against said side surface.

7. A belt grinding assembly according to claim 1 wherein said biasing means for biasing each object holder assembly toward said pre-grinding position comprises a plurality of coil springs having a pair of ends, with one end of said coil springs attached to a position on said wheel generally adjacent said wheel axis and with the other end of said coil springs being attached to the radially inward side of an object holder assembly.

8. A belt grinding assembly according to claim 1 wherein said pivotal mounting means comprises generally V-shaped cam followers mounted on each of said object holder assemblies, said V-shaped cam followers having leading and trailing portions having surfaces adapted to engage said pivoting cam means while said object holder assembly is pivoted from said pre-grinding to said post-grinding position to thereby bring the object into forceful engagement with the abrasive belt along the support surface, and
   said leading and trailing surfaces of said V-shaped cam follower diverging to prevent the workpiece from being thrown from the engagement means when the object holder assembly is pivoted from said post-grinding to said pre-grinding position after the object has been ground.

9. A belt grinding assembly according to claim 1 wherein
   said pivoting cam means comprises a cam bar mounted on said frame means and adapted to engage said pivotal mounting means,
   said pivotal mounting means comprises generally V-shaped cam followers mounted on each of said object holder assemblies, said V-shaped cam followers having leading and trailing portions having surfaces adapted to engage said cam bar while said holder assembly is moved from said pre-grinding to said post-grinding position to thereby bring the object into forceful engagement with the abrasive belt along the support surface, and
   said leading and trailing surfaces of said V-shaped cam follower diverges to prevent the workpiece from being thrown from the engagement means when the object holder assembly is pivoted from said post-grinding to said pre-grinding position after the object has been ground.

10. A belt grinding assembly according to claim 9 wherein said cam bar has a width of approximately 1.5 inches.

11. A grinding assembly adapted for use to form a new surface on an object, said grinding assembly comprising:
   frame means;
   machining means comprising:
   means for grinding a workpiece,
   means for driving said means for grinding a workpiece along a grinding path relative to said frame means; and
   workpiece feed means comprising a member having an arcuate peripheral portion having a workpiece feed axis and a workpiece feed radius defined from said workpiece feed axis;
   means mounting said workpiece feed means on said frame means for rotation of at least a portion of said workpiece feed means about said workpiece feed radius along a workpiece feed path;
   drive means for rotating at least a portion of the peripheral portion of said workpiece feed means past said machining means in a first direction; and
   a plurality of object holder assemblies having radially outward and inward sides, each object holder assembly including engagement means for releasably engaging and holding an object along said radially outward side, said object holder assemblies including:
   pivotal mounting means for mounting said object holder assemblies about object holder assembly axes that are parallel to the axis of the workpiece feed axis and which are spaced about the periphery of said workpiece feed means;
   said pivotal mounting means mounting each of said object holder assemblies with said engagement means projecting radially outwardly of said workpiece feed means for pivotal movement about said object holder axis between a pre-grinding position and a post-grinding position with pivotal movement of said object holder assembly from said pre-grinding to said post-grinding position being generally in said first direction of said workpiece feed means;
   cam means generally adjacent said machining means for pivoting each object holder assembly from said pre-grinding position to said post-grinding position during movement of the object holder assembly past said machining means to bring an object into forceful engagement with the machining means so that a radius smaller than the radius of the workpiece feed means may be ground on the object.

12. A grinding assembly according to claim 11, wherein said means for grinding a workpiece comprises a continuous abrasive belt having a backing with front and rear surfaces, and abrasive granules attached along said front surface and backup means having a support surface for said belt along said workpiece feed path; and
   said workpiece feed means comprises:
   a wheel having a periphery, a wheel axis at a right angle to said first direction, and a wheel radius defined from said wheel axis, and
   said grinding assembly includes biasing means for biasing each object holder assembly toward said pre-grinding position.

13. A grinding assembly according to claim 11 wherein each of said engagement means comprises
   movable clamp means comprising first and second jaws with said first jaw spaced from said second jaw for relative movement between a release position with said second jaw spaced freely from said first jaw to receive the object between said jaws, and an engage position adapted to firmly clamp the object between said jaws; and
   jaw actuating means for moving said movable jaws from a release position at a loading station, and for positioning said jaws in said engage position during movement of said object holders past said machining means;
   said jaw actuating means moves each of said first and second jaws to said release position at said loading station, positions said jaws in said engage position as said clamp means moves past said support surface, and moves each of said first and second jaws to said release position at an unloading position fixed relative to said frame means along the lowermost portion of said workpiece feed means, and past which unloading position said pairs of jaws are moved after movement from said loading position past said machining means;
   wherein said drive means to sequentially moves the object holder assemblies past said loading station relative to said frame means, and then past said machining means.

14. A grinding assembly according to claim 11 wherein each of said engagement means includes a first jaw, means for releasably attaching said first jaw to the radially outward side of said object holder assembly in a position fixed relative to said object holder assembly; a second jaw, and means for mounting said second jaw on said object holder assembly for pivotal movement relative to said first jaw between said release and said engage positions; said jaw actuating means includes a spring between said jaws for biasing said second jaw toward said engage position, cam means including a jaw cam follower mounted on said second jaw and a cam mounted on said frame means, said cam having a cam surface positioned for engagement by said jaw cam follower to move said second jaw to said release position.

15. A grinding assembly according to claim 14 wherein each of said plurality of object holder assemblies includes leveling means comprising cam means including a leveling cam follower mounted on said radially inward side of said object holder assembly and said cam mounted on said frame means,
   said cam surface positioned for engagement by said leveling cam follower and said jaw cam follower to move said second jaw to said release position and to level said object holder assembly in a leveled position generally midway between said pre-grinding and said post-grinding positions relative to said workpiece feed means.

16. A grinding assembly according to claim 14 wherein said means for releasably attaching said first jaw to the radially outward side of said object holder assembly comprises structural means on the radially outward side of each of said object holder assemblies adapted for defining a slot extending generally parallel to said wheel axis and having an inlet opening at one end, said first jaw having a base adapted for close fitting engagement in said slot, and means for releasably retaining said base in said slot.

17. A grinding assembly according to claim 16 wherein said radially outward side of each of said object holder assemblies has a peripheral surface, said slot is defined by a part of said peripheral surface and at least one side surface disposed at an acute angle relative to the periphery of said object holder assemblies, and said means for releasably retaining includes means for forcefully pressing said base against said side surface.

18. A belt grinding assembly according to claim 11 wherein said biasing means for biasing each object holder assembly toward said pre-grinding position comprises a plurality of coil springs having a pair of ends, with one end of said coil springs attached to a position on said workpiece feed means and with the other end of said coil springs being attached to the radially inward side of said object holder assembly.

Drawing