US2418871A

US2418871A - Apparatus for grinding bushings

Info

Publication number: US2418871A
Application number: US616705A
Authority: US
Inventors: Paul F Danielson
Original assignee: Individual
Current assignee: Individual
Priority date: 1945-09-17
Filing date: 1945-09-17
Publication date: 1947-04-15
Anticipated expiration: 1964-04-15

Description

April 15, 1947' P. F. DANIELSON 2,418,871

APPARATUS FOR GRINDING BUSHINGS Filed Sept. 17, 1945 2 Sheets-Sheet 1 /2 /9 Q /s F 62 9 11 /6 1 65 6/ INVENTOP. P4111. E DAN/ELSO/V- April 15, 1947. DANIEYLSON 2,418,871

7 APPARATUS FOR GRINDING BUSHINGS Filed Sept. 17, 1945 2 Sheets-Sheet 2 lllll ymumn V IN V ENTOR.

Patented Apr. 15, 1947 UNITED STATES PATENT OF FlCE 2,418,871 APPARATUS FOR GRINDING BUSHINGS Paul F. Danielson, Los Angeles, Calif. Application September 17, 1945, Serial No. 616,705

8 Claims.

. The present invention relates to grinding de vices of a character which may be incorporated in grinding machines, either as an attachment or as an integral part thereof.

When a series of bushings are to be externally ground to a given diameter, with the external and internal curved surfaces in concentric relationship, it is ordinary practice to fit each bushing tightly on a'tapered mandrel or other rod and to grind the bushings individually to size. While this method produces satisfactory results, at the same time it is slow and laborious. A good operator following this procedure will grind 1500 bushings to size in eight hours, Whereas the same operator utilizing the invention of this applicationwill grind the same number of bushings in one hour.

The invention has for an object an attachment which is easily installed on any existing type of grinder equipped with sliding centers, which requires but slight adjustment, is positive in its operation, assures accurate results in the work being ground, and is superior to methods of grinding work to a given concentricity now known to the inventor.

Qther objects of the invention so arranged as to permit several bushings, all of which or any of which may have irregular surfaces, to be ground sequentially to the same outside diameter.

. In the practice of my invention I may place a number of bushings upon a mandrel interposed between centers and grind the external surfaces thereof to a selected dia-meterand in such a manner that said surfaces are concentric with the bores in said bushings.

. An object of the invention is to provide a means whereby bushings carried on a mandrel are positively rotated during a grinding operation without the necessity of rotating the mandrel.

Anotherrobject i to provide means whereby bushings of uneven external diameter may be loosely placed upon a mandrel and still be ground to anaccurate external diameter, the external include a device surface of which is concentric with the bore in said bushings.

With the above and other objects in view, the invention consists in the novel and useful provision, formation, construction, association and relative arrangement of parts, members and features, all as shown in a certain embodiment in the accompanying drawings, described generally and more particularly pointed out in the claims.

. In the drawings: p

Fig. 1 is a top plan view of the improved grinding attachment shown incorporated on a grinding machine; 7

Fig. 2 is a fragmentary side elevation on an enlarged scale of the improved attachment of the invention;

Fig. 3 is a-sectional view on the line 3-3 of Fig. 2;

Fig. 4 is an end elevation of certain portions of the attachment looking in the direction of the arrow 4 of Fig. 2; and

Figs. 5 and 6 are diagrammatic views illustrating a grinding wheel, certain members of the attachment and work interposed therebetween.

Referring now with drawings:

The present invention is directed to the grinding of objects which are loosely carried on a mandrel, the mandrel being interposed between centers.

The attachment as shown in Fig, 1 at I is adapted to be incorporated in socalled arbor type grinding machines. It makes no difference so far as the attachment is concerned whether the work is fed past the grinding wheel or the grinding wheel is moved relative to the work. No par. ticular attempt will be made to describe any specific grinding machine, other than to mention that such a machine incorporates a grinding wheel 2 suitably mounted on a shaft 3, the shaft being carried in'a bearing box 4, with one end of the shaft providedwith a pulley 5. Suitable means is provided for rotating the pulley 5, such as by a continuous belt 6 passed over pulleys 5 and 1, the latter pulley being mounted on the shaft of a motor 8. The grinding machine shown likewise incorporates a table 9, movable within ways I0 of a bed I I, and said table carries a headstock 12 and a tailstock l3, both stocks having work-holding centers I 4 and I5. As is customary in grinders, either an automatic means is provided for moving the table relative to its bed, or a hand operated feed is provided, and sometimes both of such feeds. A pilot wheel for controlling table travel is shown at It, the function of which is to feed the table in one of two directions at a rate of speed desired bythe operator, At I l is shown a micrometer cross feed attachment which regulates the degree of cut or grind to be performed on the work. As is usual, such means controls movement of the grinder wheel toward or away from the work. The lever l8 locks or unlocks the tailstock, so that a mandrel may be particularity to the -means 39, constituting a bolt positioned between centers l4 and 15, or removed from therebetween,

The attachment I functions to positively rotate at a selected R. P. M. work indicated generally as [9, carried on a mandrel 20, the mandrel being interposed between centers i l and 15. The attachment l includes a block 21 formed with a slot, such as T-slot 22, for guiding movement of slide 23, the said slide having itsbase portion formed to fitwithin the T-slot, as indicated at 24. This slide carries a bracket 25, having a side Wall 26, substantially normal to the top surface 21 of the slide, and a post 28 spaced from the side wall 26 and paralleling the same. A frame designated generally as 29 is supported by the bracket 25. The said frame 29 includes a part 30 having substantially parallel side wall surfaces, which part is interposed between wall 26 and post 28, as best shown in Fig. 3. Said part is provided with an enlarged transverse bore 3|, adapted to accommodate a bolt 32 passed therethrough and held by wall 25 and post 28. Spaced from bore 3! is a bore 33, which is elongated in form and has a counterbore at 34. A bolt 35 has its head 36 received within the counterbore, the opposite end of said bolt being passed through bore 3! in wall 26 and secured in position of service by a nut 38. It will be seen that the frame 29 may have its part 30 reciprocated a slight distance between the

members

25 and 28 of bracket 25. This reciprocation is controlled by adjustment having threaded engagement with a threaded bore 40 in the end 'of member 35. The shank of the said bolt is passed through an enlarged opening 4| of plate 42. The head of the bolt engages the outer surface of said, plate andtnus limits movement of the frame '29 in one directionh This plate is secured to wall--26, t 43 by means 44. Springs "45 are interposed between the said plate and the end 45 of member 30. Any suitable means may be used for holding the springs in positio'n of service, such as by forming pockets 41 in both 'thesaidplate and the end 46 for confining end portions of said springs, see Fig. 2. "Frame 29 has an enlarged-head portion 48, which is offset relative to portion 30. This con- 'struction provides two pairs of upper and lower bearing'members' 49, 5B, 51 and 52, between'pairs of which are

shafts

53 and 54. Mounted on the shafts are rollers '55 and 56. The

shafts

53 and 54 havekeyed thereto gears 5'! and 58. The frame 29 rotatively carries a gear 59, the teeth of which are in mesh with teeth of the gears 5! and 58, and a gear likewise carried by the frame has the teeth thereof in engagement with the teeth of gear 59. Gear 62 is adapted to be driven by a motor Bl. In the embodiment shown the motor shaft drives a speed reducer 62, the shaft of which'reducer turns the universal coupling 63, to which is connected a link 64, which link through a universal coupling 65 is connected to gear, 60.-

A plate 56 is secured to the wall 26 by means 61, the said plateoverlapping the roller 54. The overlapped portionof the plate carries a spring loaded screw 58, the end of which screw engages the onset head. 48. The purpose of such an arrangement is to stabilize the bearing members of the. head. The block 2| is provided with a SU-PPQItv 69 for a bell crank lever 10. The said support is provided with an elongated slot I l, and a bolt [2 is passed through the bell crank at its apexand through said slot H. The short, lever 13 is pinned to link 14, the link in turn being 4 pinned to slide 23. The longer lever of said bell crank carries a hand grip whereby the lever may be easily rocked.

The operation, uses and advantages of the invention are as follows:

It is to be noted that roller is of greater diameter than roller 56. These rollers function in the capacity of pressure drive means for the work; specifically the larger roller provides a tangential driving force against the work to turn the work at a given rotational speed, while the smaller roller 55 functions to retard the rotation of the work or act as a means for taking up any rotational slack, all to the end that the work will be rotated at a continuous speed, which is to say there will be no interruptions in the rotation. It is of course obvious that both rollers are rotated at the same speed, but that the larger roller has a greater circumference than the smaller roller, hence when the two rollers contact the work the smaller roller tends to retard rotation of the work, the resultant rotation of the work is therefore constant and without interruption.

After the block 2! has been fastened to the bed of the grinding machine and so positioned that the plane of the grinding wheel 2 transversely cuts the pressure drive rollers, the driven gear is connected with the motor 6! through suitable reduction gearing 62. Thus the

pressure drive rollers

55 and 56 are positively driven through gears 51-563 inclusive, the pressure drive rollers revolving in the same direction, as indicated by the arrows on said rollers in Figs. 5 and 6.

It is obvious that there must be a difierence in rotative speeds between the pressure drive rollers and the grinding wheel; and it is further obvious that in order to perform a proper grinding operation upon the work that the work should be rotating prior to contact with the grinding wheel. For this reason the

rollers

55 and 55 are of such length as to progressively rotate the work in advance of contact of the work with said grinding wheel, as illustrated in Fig. 1. The arrangement is such that the rollers continue to rotate the work until the work has been freed from grinding wheel contact. Preferably the two rollers are formed of a material adapted to positively drive the work, and I may utilize for the material of said rollers any of the well known rubberized bonded abrasives now on the market.

If the work to be ground constitute bushings, the said bushings, irrespective of uneveness of external surface, are assembled on a mandrel so as to extend substantially the length of said mandrel with the bushings substantially free to rotate thereon. The mandrel, such as 2!], is then interposed between the centers l4 and I5 of the headstock and tailstock. The index dial l l is adjusted so that the periphery of the grinding wheel 2 is positioned to remove material from the work to give the work a selected external diameter. In the arrangement shown, the work, if it happens to be bushings, may have difierent external diameters or bores; however, regardless of bore diameter, the external diameter of all the bushings will be the same after a grinding operation and the external surface will be concentric with the bore insaid bushings.

As previously pointed out, there is a difference in diameter between the

pressure driving rollers

55 and 56. Both of these rollers contact the work as indicated in Figs. 5 and 6. These rollers are brought into contact with the work when the bell crank 15 is moved to the position shown in Fig. 2.

When the bushings have a like internal diam- Slide 23 eter, the said bushings will fit fairly'tightly on the mandrel, yet are capable of rotating, as for instance illustrated in Fig. 5. If however the internal diameter of the bushing is larger than the diameter of the mandrel, a condition similar to that shown in Fig. 6 may arise. However, difference in internal diameter of the bushing will not change the operation of the attachment, and the external surface of the bushing will be ground concentric with the bore in said bushing with an O. D. the same as for all other bushings. This results by reason of the construction of the attachment, wherein viewing Fig. 6 it will be observed that the pressure driving rollers contact two portions of the periphery of the work and force'the work into eccentric relationship relative to the mandrel. This eccentric relationship is maintained during a grinding operation, with the result that the inner bore and the external cylindrical surface of the bushin are concentric, a feature of great importance and one which so far as the inventor is aware is not accomplished by grinding machines now known to him.

The pressure necessary to be exerted against the work by the rollers in order to positively turn the same, may be determined experimentally by the operator, whereupon the bolt 12 is tightened at a given position within the slot 1 I. Preferably the lever when finally adjusted extends slightly over center. When the bell crank is swung from the position of Fig. 2 to the left of the showing of said figure, lever 13 will assume a vertical position and move the link, thus moving the slide 23, which causes disengagement of the

rollers

55 and 56 from the work. Having once determined the pivot point for the bell crank lever, the operator need pay no further attention to the adjustment for a given 0. D. of bushing, but simply feed the table 9 by turning the pilot wheel l6 so that the work is progressively moved past the grinding wheel 2. Upon completion of a grinding operation on all of the work, the operator removes the mandrel with the work thereon from between the centers and places on the mandrel further bushings to be ground.

If we assume that the thickness of the bushing relative to its inner bore varies at given points, then as the

pressure drive rollers

55 and 56 rotate the work, the frame 29 may move relative to bracket 25. Thus the rollers at all times follow the contour of the surface of the work and move either forward or backward, due to the construction shown in Figs. 2 and 3,.wherein it is to be observed that the frame is capable of movement between the bracket members 26 and 28 against pressure exerted by the springs 45. These springs at all times urge the rollers towards the work and the extent of the forward movement of the rollers towards the work is regulated by bolt 39.

Various refinements of details may be incorporated in the attachment, such as for instance the guard 15 attached to the forward end of the This guard functions to prevent the coolant from entering between the guide for the slide and the block and in any manner impeding its operation, and there may be provided a guard between the grinding wheel and the work, so that the coolant liquid will not contact the attachment.

The method of securing the block 2| to the bed of the lathe is not detailed, but any suitable means may be utilized, and preferably the device may be bolted to the grinder bed.

Iclaim: y

1. The combination with a grinder having a driven grinding wheel adapted to have regulated contact With work, a movable headstock and a tailstock provided with centersbetween which centers is placed a mandrel upon which cy1indri-' cal objects constituting the work are positioned to be ground, the said work being rotatable upon said mandrel; of a device for positively rotating the work as the headstock'and tailstock are moved to progressively bring the Work into grinding wheel engagement; said device including a frame, a pair of spaced apart rollers rotatably carried by said frame, a slide, and resilient means between said slide and said frame for normally urging said frame in one direction; means for positively rotating both rollers and means for moving said slide to position the rollers in work engagement under the resilient action of said first means. 2. The combination with a grinder havinga driven grinding wheel adapted to have regulated contact with work, .a movable headstock and a tailstock provided withcenters between which centers is placed a mandrel upon which cylindrical objects constituting the work are positioned to be ground, the said work being rotatable upon said mandrel; of a device for positively rotating the work as the headstock and tailstock are moved to progressively bring the work into grinding wheel engagement; said device including a frame, a pair of spaced apart rollers rot-atably carried by said frame, a slide, and resilient means between said slide and said frame for normally urging said frame in one direction; means for positively rotating both rollers and means for moving said slide to position the rollers in work engagement under the resilient action of said first means, the said last named means comprising an adjustably positioned lever.

3. The combination with a grinder having a driven grinding wheel adapted to have regulated contact with work, a movable headstock and a tailstock provided with centers between which centers is placed a mandrel upon which cylindrical objects constituting the work are positioned to be ground, the said work being-rotatable upon said mandrel; of a device for positively rotating the work as the headstock and tailstock are moved to progressively bring the work into grinding wheel engagement; said device including a block for attachment to a fixed portion of the grinder and positioned opposite to and in the plane of the said grinding wheel, a slide carried by said block and movable relative thereto, a frame and means for securing said frame to said slide; a pair of work engaging rollers carried by the frame and adapted to be brought into work engagement, and means for positively rotating said rollers.

4. The combination with a grinder having a driven grinding wheel adapted to have regulated contact with work, a movable headstock and a tailstock provided with centers between which centers is placed a mandrel upon which cylindrical objects constituting the work are positioned to be ground, the said work being rotatable upon said mandrel; of a device for positively rotating the work as the headstock and tailstock are moved to progressively bring the work into grinding wheel engagement; said device including a block for attachment to a fixed portion of the grinder and positioned opposite to and in the plane of the said grinding wheel, a slide carried by said block and movable relative thereto, a

frame and means for securing said frame tosaid slide: a pair of work engaging rollers carried by the frame and adapted to be brought into work engagement, means for positively rotating said rollers, and resilient means for maintaining said rollers in said work engagement.

5. In a device of the character disclosed, a frame, a pair of spaced apart rollers rotatably secured to said frame, a slide provided with substantially parallel side walls between which a'portion of said frame is positioned, means carried by said side walls for movabl'y mounting the frame therebetween, and resilient means for urging said frame in one direction; means for rotating said rollers and adjustable means for moving the said slide to position said rollers in work engagement. 6. In a device of the character disclosed, a pair of friction rollers for contact with work, means for simultaneously turning said rollers, one of said rollers being of lesser diameter than the other thereof, to thereby efiect constant rotation of the work.

'7. The combination with a grinding wheel, a mandrel upon which a number of bushings are placed for rotation, the said mandrel adapted to be fed past the grinding wheel to in turn grind the bushings, of a pair of friction type drive rollers for contact with the bushings; and adapted to cause rotation of the bushings in advance of contact with the grinding wheel and during contact therewith; one of said rollers having a greater diameter than the other thereof; and means for rotating said rollers at a constant speed and whereby the smaller diameter roller retards rotation of the bushings to thereby effect an uninterrupted-rotation thereof.

8. The combination with a grinder having a driven grinding wheel adapted to have regulated contact with work, a movable headstock and tailstock provided with centers between which centers is placed a constant diameter mandrel upon which a plurality of bushings constituting the work are positioned to be ground, the said bushings floating upon said mandrel; of a pair of drive rollers for rotatin the bushings in advance of and during contact with the grinding wheel as the headstock and tailstock are moved, one of said rollers being of lesser diameter than the other roller, and the roller of greater diameter functioning as the main driving roller for said bushings, and the roller of lesser diameter functioning to pick up any rotative slack in the bushings due to any uneven surface on said bushings, to thereby effect a constant rotative speed of the bushings.

PAUL F. DANIELSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,345,308 Wallace Mar. 28, 1944 1,845,122 Briney Feb. 16, 1932 1,874,301 Jones Aug. 30, 1932 1,878,116 Deutsch Sept. 20, 1932 2,023,720 Asbridge Dec. 10, 1935 1,735,333 Olson Nov. 12, 1929