US2137821A - Grinding machine - Google Patents

Description

O 22, 1938. H. w. DUNBAR Er AL 2,137,821

GRINDING MACHINE Filed May 12, 1957 "a Sheets-Sheet 1 I I57 J ""f q 2 MM [82 n rl54 0 3 l8 HOWARD l V. DUNBAR 776 HERBERT 5'. INDGE M EQW I Nov. 22, 1938. H. w. DUNBAR ET AL 2,137,821

GRINDING MACHINE Filed May 12, 1937 3 Sheets-Sheet 2 H 3 HUWAE'D W DL/NEAR HER ERT S. IND-GE.

amt/W Nov. 22, 1938 H. w. DUNBAR ET AL 2,137,321

GRINDING MACHINE I Filed May 12, 1957 3 Sheets-Sheet 5 HUWARJJ I/V. Duh/BAR HERBERT SQINDG'E Patented Nov. 22, 1938 UNITED STATES PATENT OFFICE GRINDING momma Massachusetts Application May 12, 1937, Serial No. 142,082

2 Claims.

The invention relates to grinding machines. One object of the invention is to provide a continuously acting or automatic grinding ma chine of simple construction which is eflicient 5 in practical operation. Another object of the invention is to provide a grinding machine of high production capacity. Another object of the invention is to provide a through feed grinding machine having no work rests, whereby maladjustments due to wear of the work rests are avoided and replacement of work rests in obviated. Another object of the invention is to provide a continuously operating grinding machine so organized that adjustments may be readily made. Another object of the invention is to provide a grinding machine of the characteristics indicated in which the work piece is contacted only by the wheels and with apparatus to reshape the wheels to maintain accuracy in the grinding of work pieces. Another object of the invention is to provide a continuously operating through feed grinding machine capable of turning out work pieces accurately ground to a true right circular cylindrical contour. Other objects will be in part obvious or in part pointed out hereinafter.

The invention accordingly consists in the features of construction, combinations of elements, and arrangements of parts as will be exemplified in the structure to be hereinafter described and the scope of the application of which will be indicated in the following claims.

In the accompanying drawings showing one of many possible embodiments of the mechanical features of this invention,

Figure 1 is a front elevation of the grinding machine;

Figure 2 is a vertical transverse sectional view.

of a truing wheel operating mechanism, the section being taken on the line 2--2 of Figure 1;

Figure 3 is a view partly in elevation and partly in vertical section taken from the right hand end of the machine;

Figure 4 is a horizontal sectional view of the provide a firm foundation for the machine ele'-' ments. Referring now to Figure 3, uprising from the base 20 and suitably secured thereto or in- 55 tegrally formed therewith is a column 2| which,

truing wheel actuating mechanism, the section as better shown in Figure 5, has vertical ways 22 and 23. Still referring to Figures 3 and 5, a vertically movable slide 24 has ways 25 and 26 complementary to ways 22 and 23 respectively and thus the slide 24 is mounted for vertical movement, and the area of the surface on the several ways is suflicient to hold the slide 24 from any movement, lateral, torsional, or otherwise, excepting vertical movement which is controlled as hereinafter described.

Referring now to Figures 1 and 3, the base 20 has in front of the column 2| flat horizontal plane surfaces 28, 29 and 30, the surfaces 28 and 30 being in the same horizontal plane and being separated from the surface '29 by reentrant inclined plane surfaces 3| and 32 which, together with the surface 29 constitute ways for a pair of carriages 35 and 36 shown in Figure 3. The carriages 35 and 36 have cooperating dove-tailed ways fitting the ways formed by the surfaces 30, 3| and 32 and are movable horizontally fore and aft of the machine, that is to say parallel to the plane of Figure 3.

Referring now to Figures 3 and 5, the slide 35 supports an abrasive wheel 40 which is preferably a true right circular cylinder. The slide 36 supports a wheel 4| which is also preferably a true right circular cylinder. The axes of the wheels 40 and 4| are at all times parallel to each other according to the preferred form of this invention.

Referring to Figures 3 and 5, on the front of the machine we provide hand wheels 43 and 44, operating screw shafts 45 and 46 respectively which engage nuts 41 and 48 respectively, which nuts 41 and 48 depend from slides 35 and 36 respectively. Thus each wheel 40 and 4| can be moved fore and aft of the machine.

Considering now the construction and mounting of the wheels 40 and-4|, each preferably con- Sists of a plurality of sections as shown, mounted bywheel flanges 5| and 62 upon shafts 60 and 6| respectively. Referring to Figure 1, uprising from the right hand end of the carriage 35 and integrally formed therewith is a journal support 62 for the wheel shaft 60. The left hand end of the carriage 35 has dove-tailed ways 53 supporting a slide 64 with complementary ways, which slide 64 has a journal portion 65 for the shaft 60. Similarly uprising "from the slide 36 is an integral journal portion 66 supporting one endof the shaft 6| and at the other end of the slide 36 are, as shown in Figure 3, dove-tailed ways 61 supporting a slide 68 having a journal portion 69 for supporting the other end of the shaft 6|. This construction facilitates removal of the wheels 48 and 4| when they have been worn down below permissible operating size. We provide bolts 18 and 1| respectively extending through a slotted portion of the slides 54 and 88 respectively to lock these slides to the slides 35 and 38 when the journals have been properly adjusted.

Considering now the drive for the wheels 48 and 4| which are rotated in the same angular direction, we provide a driving motor 15 whose armature shaft 18 is connected by a coupling 11 to a shaft 18 journalled in a casing 18. A worm 88 upon the shaft 18 meshes with a worm wheel 8| whose shaft 82 is journalled in the casing 18. Keyed to the shaft 82 is a double V-groove pulley 83 driving by means of belts 84 pulleys 88 and 81 keyed to the shafts 88 and 8| respectively. The belts 84 also pass around an idler pulley 88 rotatable on a stud 8| which extends from a bracket 82 secured to the machine base.

By the construction so far described we provide two wheels 48 and 4| with a reduction gear drive to drive them at a slow rate of speed. These wheels 48 and 4| are true cylinders and mounted on parallel axes but can be adjusted toward and from each other. They are rotated in the same angular direction and owing to the resiliency of the belts 84 considerable adjustment can be made without changing belts particularly as the course of the belts is such that considerable movement of the wheels may be made without greatly stretching or slackening the belts. These wheels 48 and 4| rotating slowly and at the same rate of speed support and rotate the work piece W. The wheels are preferably made of resinoid bonded fused alumina abrasive grain of fine grit size and so grip and rotate the work but do not abrade it. Any other wheel composition known may be used, for example other abrasives such as silicon carbide or quartz might be used bonded with any known bond such as the vitrified ceramic bonds, shellac, o1 rubber. In fact when grinding certain work pieces, wheels having no abrasive whatsoever might be used to support and rotate the work piece, such as wheels made of vulcanized rubber, although we prefer to use a bonded abrasive wheel having fine grit size abrasive.

The work piece is fed through the machine and ground while so moving by means of a grinding wheel 83 which is fully adjustable in a vertical direction and is mounted on an axis skewed with respect to the axis of the wheels- 48 and 4|, the angle of inclination being also adjustable. This wheel may be manufactured as a true cylinder but is dressed or trued in a manner to be hereinafter described into the shape of a pseudo-sphere whereby a line contact-between it and the work piece is achieved although the work piece does not move parallel to the axis of the wheel 83. It 'is the angle of inclination of the wheel 83 with respect to the path of travel of the work piece as determined by the wheels 48 and 4| which feeds the work piece through the machine. Preferably the wheel 83 rotates in the same angular direction as the wheels 48 and 4| but at a much faster speed.

Referring now to Figure 3, attached to or formed integrally with the upper end of the vertical slide 24 is a large overhanging support 84. Referring now to Figure l, the overhanging support 84 has a horizontal under surface 85 and overhanging ways 86 and 81. An inverted angularly adjustable table 88 has ways 88 and I88 fitting the ways 86 and 81, whereby the table 88 is supported. The table is further centered by a trunnion |8I projecting therefrom into a bored hole I82 in the overhanging support 84. It will be apparent that the angular position of the table 88 may be readily changed. In this embodiment of the invention alteration of this skew angle is made by means of a lead hammer or the like and the friction due to the great weight of the parts holds the table 88 in a given angular position.

The upper wheel 83 is a grinding wheel made from any of the abrasives hereinbefore mentioned or any other, and bonded with any of the bonds hereinbefore mentioned or any other, the abrasive being preferably coarser than the abrasive in the lower wheels. Referring now to Figures 5 and 6, the grinding wheel 83 is driven at a relatively high speed, for example of the order of six thousand surface feet per minute, by means of an electric motor I83 which is secured as shown in Figure 5 to the side of the slide 24. The armature shaft I84 of the motor I83 is connected by universal joints I85 and I88 and a connecting telescoping shaft I81 to a shaft I88 which is journalled in a hollow journal support I88 depending from the table 88 at the left hand end thereof.- This journal support I88 is shown in section in Figure 6 and includes a support for a roller bearing II8 journalling one end of a spindle III for the wheel 83. A further roller bearing 2 which is supported by the journal portion I88 also supports the spindle III and between the roller bearings H8 and H2 is a helical gear I I3 which, as better shown in Figure 1, meshes with a helical gear I mounted upon the shaft I88. Thus the spindle III is rotated by the motor I83 and a positive connection is maintained in all positions of angular adjustment of the wheel 83, by the provision of the telescopic connection I81 and the universal joints I85 and I86.

Referring to Figures 1 and 6, the right hand end of the spindle III is journalled in a roller bearing 5- supported by a depending journal portion II8 which has a dove-tailed slide portion II1 mounted on slide ways I I8 formed on the under side of the table 88. After the parts are assembled the slide portion I I1 may be secured in position on the slideway 8 by means of tightening bolts I28 extending through a slot |2I formed in the slideway II1, as shown in Figure 3.

For convenience of assembly the plurality of sections of abrasive material of which the wheel 83 is formed are mounted upon a sleeve I22 having a flange portion I23 at one end, and screw threads receiving-a flange I24 and nut I25 at the other end. This construction may be and preferably is adopted also for the lower wheels 48 and 4|. 4

The upper wheel 88 is movable upwardly and downwardly, on the one hand in order to adjust the size of the work receiving throat, and on the other hand, to position it for truing in the manner which will be presently described. Referring now to Figure 3, the vertical slide 24 has a platform I38 upon which is mounted a motor |3I whose armature shaft I 32 is coupled by means of a coupling I33 to a shaft I34 which is journalled in a casing I35 and which has formed thereon a worm I36 meshing with a worm wheel I31. The worm wheel I31 is fastened to a shaft I88 also journalled in the casing I35. Fastened to the shaft I38 is a worm I38 meshing with a worm wheel I48 which is integral with a nut I 4| support I43 to the column 2|.

surrounding a screw shaft I42. The screw shaft I42 is attached, as shown in detail in Figures 3 and 5, by means of a floating and self-aligning A full description of the details of this self-aligning support is not necessary to an understanding of the present invention since any other manner of attachment may be utilized and a self-aligning support is provided to take care of imperfections or inequalities of machining the parts. A full description thereof, however, will be found in copending application Serial No. 5,271 filed February '6, 1935 which has become Patent No. 2,087,874 dated July 20, 1937. I

By energizing the motor I3I which is controlled by the switch I44 the slide 24 may be moved vertically at any time. Fine adjustments may be better made with a hand wheel I45 which, as shown in Figure 3, is mounted on the front of a shaft I46 coupled by means of a coupling I41 to the shaft I34.

The wheels are dressedand trued from time to time, and the wheel 93 is formed into a pseudosphere wheel by dressing apparatus fully described in copending application Serial No. 5,271 filed February 6, 1935 which has become Patent No. 2,087,874, dated July 20, 1937 and as described and claimed in application Serial No. 132,753 filed March 24, 1937 which is a division from said application Serial No. 5,271.

Referring now to Figure 1, at the front of the machine and attached to the base 20 is an apron I50. As better shown in Figure 3, the apron has ways II, I5I supporting a slide I52 for movement in a horizontal direction. Referring now to Figure 2, between the ways I5I, I5I is a rack I53 which is secured to the apron I50. Meshing with the rack I53 is a small gear I54 mounted upon one end of a shaft I55 journalled in the slide I52. Fastened to the other end of the shaft I55 is a bevel gear I56 with which, as better shown in Figure 4, mesh a pair of bevel gears I51 and I58.

Referring now to Figure 1, an electric motor I89 is mounted upon a platform I6I connected to the slide I52. The motor I60 drives by means of a belt I62 a pulley I63. As better shown in Figure 2, the pulley I 63 is integral with the shaft I64 which is mounted in journals I65 and I66, the former in. a casing I61 which encloses the gears I55, I51 and I58, and the latter journal I66 being in the main part of the slide I52. Fixed on the shaft I64 is a worm I68 meshing with a worm wheel I69.

Referring now to Figure 4, the worm wheel I69 is pinned to a shaft I on which are mounted the bevel gears I51 and I58. A sliding clutch collar I1I having teeth at both ends is keyed to the shaft I10 and adapted to engage clutch teeth formed on the inner ends of the bevel gears I51 and I58. Referring to Figures 2 and 4,a fork I engages the clutch collar I1I extending into a groove I16 thereof. The fork I15 is pivotally connected to an arm I18 which is pinned to a shaft I19, to the other end of which is pinned a hand lever- I80. As shown in Figure 1, an operating rod I8I is connected with the upper end of the arm I18, being mounted on the pin I82 which pivotally connects the fork I15 to the arm I18. Another rod I83 is pivotally connected to the manually operating lever I60. The rod I8I is positioned to contact a stationary dog I85 extending horizontally from the right side of the apron, while the rod I83 is positioned to contact a stationary dog I86 connected to the left are parallel to the ways I5I.

hand side of the apron I50. When the motor I60 is energized, the slide I52 may be caused to traverse upon the ways I5I, I5I by swinging the operating lever I80 to the right or left, thus engaging one or the other of the gears I51 or I58 with the shaft I10, thereby driving the gear I54 to traverse the slide or carriage I52. Upon reaching the end of its stroke, the slide or carriage I52 is automatically stopped by engagement of one or the other of the rods I8I, I83 with the dogs or stops I85, I86, respectively.

Referring now to Figure 3, extending upwardly from the carriage I52 and rigidlyattached to it s a dressing wheel standard I90. dressing wheel standard I90 are slide ways I9I supporting vertically movable slide I92. By means of a hand wheel I93 operating a screw I94 engaging a nut I95, Figure 1, secured to the slide I 92, the slide I 92 may be raised and lowered. The screw I94 is held to the standard I90 by means of a thimble and collar I91 and I98. Journalled in the slide I92 is a spindle I99 supporting a dressing wheel 200. By means of a pulley I, a belt 202 and a pulley 203 driven by the motor I60, as well as idler pulley 204, the pulley 20I, and therefore the spindle I99,'is

driven when the motor I60 is energized, thereby rotating the dressing wheel 200. As clearly shown in Figure 3, the dressing wheel 200 has a torc surface periphery. In other words the wheel 200 is in the form of a disk with a toric periphery. As a result, when the rotating wheel 200 is traversed in contact with each of the wheels 40, 4| and 93, the wheels 40 and M are dressed to true cylindrical surfaces as their axes The wheel 93, however, is shaped to a pseudo-sphere such that a work piece may be moved along it in contact with it, without distortion, the work piece also being in contact with the wheels 40 and M.

The wheel 290 is rotated at a fairly high peripheral velocity, while the wheels 40 and M rotate at a slow speed. The 'wheel 93 rotates at a faster or grinding speed. The wheel 200 is traversed for dressing purposes very slowly so that all parts of the wheels 40, 4I and 93 are con tacted by the dressing wheel 200.

Any type of work feeding troughs and work removing troughs may be used such as those shown in pending application Serial No. 5,271, filed February 6, 1935. Excepting when the wheels are being dressed, the dressing instrumentalities are kept at the left hand end of the machine, as shown in Figure 1. Preferably the work piece is moved from right to left in Figure 1 and under these conditions the wheels all revolve'clockwise. On account of the skew or inclination of the grinding wheel 93 the work piece is forced slowly through the grinding throat, from right to left, Figure 1, that is to say, away from the observer in Figure 3.

The machine is adapted particularly for grinding work pieces that have already been machined or cold rolled or the like to within close tolerances and under such conditions can act as a continuous grinding machine, grinding many work pieces at a given instant. That is to say, many work pieces are in the grinding throat at a given time and are being ground by the wheels. In order to produce pressure upon the work piece or work pieces we locate the upper wheel 93 so that the grinding throat is slightly less in size than the work piece, by a matter of a few ten thousandths of an inch. The inevitablespring in the parts by reason of the G construction as clearly On the at three distinct lines.

shown, causes separation enough to allow the work piece to enter and be ground.

With regard to the relations of the three wheels which form a work receiving throat, it will be seen that each wheel is located between two wheels and to one side of lines connecting the axes of the other two wheels. In the case of the two wheels 40 and 4| these lines connecting the axes form a plane. In the case of any pair of wheels including the wheel 93, these lines do not form a plane but nevertheless define a surface, and the third wheel is always to one side of said surface and between the two given wheels. With such a relationship of wheels, two of them being parallel and the third being dressed as herein described, a work piece receiving throat is formed in which the work piece is contacted The wheel 20!! is preferably compounded of very hard abrasive material, such as silicon carbide, bonded together with a suitable bond, for example vitrified ceramic bond, in such structure as to form a wheel of high grade hardness. Under such conditions and with a slow traverse feed it can readily cut the other wheels.

A particular advantage of the invention residesin the combination above defined whereby a. work piece is rotated and ground by three wheels without the use of any steady rests or rest surfaces. Where a work piece is rigidly held by a chuck and rotated, or where a work piece is held between the lathe type of centers and rotated, and then ground with a grinding wheel, a truly cylindrical work piece is produced within very small limits clue to chattering or the like.

Centerless machines having stationary work rests have been found in many instances to produce work pieces of more .or less constant diameter but yet varying from true circular form. A curve can be drawn of constant diameter which is yet not circular. The present machine is found to produce more nearly circular work pieces than centerless machines having work shoes and rests. It will be understood that in the foregoing, dimensions of the order of a ten thousandth of an inch are referred to.

It will thus be seen that there has been provided by this invention apparatus in which the various objects hereinabove set forth together with many thoroughly practical advantages are successfully achieved. As many possible embodiments may be made of the above invention and as many changes might be made in the embodiment above set forth, it is to be understood that all matter hereinbefore set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

Certain features of this machine will be found described in our copending application Serial No. 139,226, but the subject matter claimed in that application is distinct from the subject matter claimed in this application.

We claim:

In an abrading machine, a pair of journals, a spindle extending between said journals upon which a cylindrical wheel may be mounted, a second set of journals parallel to the first, a spindle parallel to said first spindle extending between the second set of journals and upon which a cylindrical wheel may be mounted, means to adjust the journals to move the spindles toward and from each other but maintaining the parallel relation, a third pair of journals and a third spindle extending therebetween upon which a cylindrical wheel may be mounted, adjustment means for the last set of journals to skew the spindle carried thereby slightly to the other spindles, a toric dressing wheel, means to rotate said toric dressing wheel on an axis parallel to the plane of the first two spindles, means to traverse said toric dressing wheel between the first two spindles and in a direction parallel to the axis of each thereof wherebythe toric wheel will true wheels on the first named three spindles so that, when the spindles are adjusted, an abrasive throat is formed to abrade a work piece the diameter of which is the toric diameter of the toric wheel.

2. In an abrading machine, a pair of spindles, a pair of journals for each spindle holding them in parallel relation, means to move one pair of journals toward and from the other pair of journals without destroying the parallelism, a slideway in parallel to the spindles, a slide on the slideway, a spindle on the slide perpendicular to the slideway and parallel to the plane of the first named spindles, a toric wheel on the spindle on the slide, means to revolve the toric wheel, and means to move the slide on the slideway whereby the toric wheel will true wheels mounted on the first mentioned pair of spindles to form a. work rotating and guiding support.

HOWARD W. DUNBAR. HERBERT S. IN'DGE.

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