US1876202A - Surfacing machine - Google Patents

Description

Sept. 6, 1932. s, R ELL 1,876,202

SURFACING MACHINE Fild Feb. 13.. 1950 2 Sheets-Sheet l A TTORNEYS.

Sept. 6, 1932. s. R. CAMPBELL SURFACING MACHINE Filed Feb. 15. 195.0

2 Sheets-Sheet 2 III M llll WITNESSES INVENTOR ,Sem 1?. Campbell,

v TTOR NEYS.

Patented Sept. 6, 1932 3mm mm OFFICE sn'rn R. cnifrnnrgn, orynnooxns Mints, rENNsYLvANIA "suarAcr'Ne vmornnn Application filed February 13, 1930. Serial No. 428,112.

This invention, while relating generally to surfacing machines, has (particular .application to rotary lapping machines of the, type shown in U. S. Letters Patent to VVyllis H 5 Markland, No. 1,515,743, issued November of a work-holder supportedby and adapted to rotate with the surrounding annulus. Machines :of thisvtype arecommonly used for reconditioningor lappingsmall valves, such as the moving parts of triple valves, universal valves, distributing valves,v and the like.

The object vofthe present invention is to increase the capacity and the efliciency of such machines, and to this end I accomplish by the provision of means which enable the; continuous operation of the machine LOVGI'. a comparatively long time without the necessity.

of resurfacing the grinding plate I Iereto fore it has been characteristic of such ma chines that the several articles being groundi travel over a variety of overlapping courses on the grinding plate, by reason .of the ec'-; centric relation of thegrinding plate'andv work-holder, but each article of work repeats its own course, so that the Wearonthe' grinding plate, while somewhat. distributed over its surfaces, is nevertheless non-uniform.

49 Accordinglythe grinding, plateshave to be resurfaced quite frequently, and this isa factor tending to limit. materially the capaci:

ty of suchmachines. I On the other hand, the present-invention is characterized by a-relation between workholder and grinding plate which permits each article of work to travel over a'different course on' the grinding plate at each rotation so that a particular point on one item of work will describe an infinite number of courses withoutrepetition. Furthermore, the work may be so distributed that these courses will cover the entire surface of the grinding plate, with the result that there is a substantially uniform wear on the I grinding plate, thus eliminating the necessity of truing the'surfaceof-the plate, save after a long period of operation.

fOther objects and; advantages attained by my invention will be apparentfrom the detailed description, which follows hereinafter, of" one form which the invention may take.

The description has reference to th 1 illustrated in the acment of the invention companying drawings,

of which:

h Fig. Iis a top plan view of a rotarylapping machine ofmy invention with one work-holding tray in position'and the other removed, certain parts being broken away for clearnessf in illustration.

Fig. II is aside elevationof the upper part of thesame with a portion of the, grinding plate and its surrounding annulus shown in cross-section.

.- Fig. III is a cross-sectional view, of the machineof Fig. I taken along the lines III III of Fig. I; and,

"I ig. IV'is a detailed cross-sectional View o'f-the brake 'mechanismshown in Fig. III.

The machine shown is a rotary lapping machine comprising generally a rotary grinding plate ;1, a surrounding carrier'Z in the form of. an annulus or bowl eccentric to'the grinding plate, and mechanism for causing the grinding plate-to rotate in one direction and the bowliin a reverse direction, the grinding plate in'the instance shown being adapted to rotate at a speed five times greater than that of the bowl. f

The mechanism for driving the grinding plate 1 and the annulus or bowl 2 is similar to that shown in the above mentioned Letters Patent of Wyllis H. Markland and forms no part of this invention. Briefly it comprises a frame 3, which may conveniently be a part of a table or work bench, and a number of shafts and gears for transmitting power applied at the pulley 4 to the grinding plate shaft 5 and to the gear ring 6 on the annulus 2. The grinding plate shaft 5 is driven by a pulley shaft 7 through bevel gears 8 and 9. An additional gear 10 on the grinding plate shaft 5 engages an idler 11 which in turn drives a pinion 12 on a shaft 13. The shaft 13 through an additional pinion 14 drives the annulus 2, the pinion 14 engaging the gear ring 6 on the underside of the annulus 2, causing the same to rotate about the eccentric hub 15 on the frame 3. On the grinding plate shaft 5 is a driving plate 16 provided with a screw 17 near its perimeter. The screw 17 is adapted to engage one of a set of similar screws 18 used for levelling the grinding plate. This furnishes a positive drive, while permitting the grinding plate to be easily removed. Suitable arrangement, which need not be here described, is made for oiling the various shaft bearings.

The mechanism thus far described effects the opposite rotation at a predetermined speed ratio, say five to one, of the grinding plate 1 and the surrounding eccentric annulus 2.

Centrally of the grinding plate 1 there is an annular recess 19 designed to accommodate a floating plate 20. This plate 20 has merely a frictional engagement with the grinding plate 1 so that it will float on the grinding plate unless otherwise restrained. A disc 21 is internally threaded to engage corresponding threads on the floating plate 20, and a set screw 22 is provided to enable an adjustment between the disc 21 and floating plate 20 for reasons hereinafter pointed out, these parts being held in fixed relation by he set screw 22 while the machine is in operation. The floating plate 20 and the superimposed disc 21 together constitute a workholder support.

Eccentrically mounted on the disc 21 are a threaded pin 23 and a ball race 24, these parts serving as a bearing for the workholder or carrier 25. The pin 23, though off center from the grinding plate 1, is centered with respect to the annulus or bowl 2, when the parts are in the position shown in the drawings. The work-holder 25 is always eccentric to the grinding plate 1 and at times concentric with the annulus or bowl 2. A

a cap 26 engages thefupper threads of the pin 23 and serves to hold the work-holder 25 in place, while permitting its ready removal. The cap 26 is recessed at 27 so that it does not come in frictional contact with the workholder 25.

The work-holder 25 comprises a spider frame adapted to accommodate in its semicircular openings 28 removable trays 29 which carry the work to be ground. The trays 29 are provided with openings 30 of a size to accommodate the particular type of work. I preferably employ a series of such trays with openings of a variety of shapes suiting the parts which are customarily resurfaced on the machine. The trays 29 are retained within the work-holder 25 by flexible metal straps 31 having slots 32 engaging pins 33 on the work-holder which permit a limited sliding movement of the straps around the work-holder. The straps 31 are provided with lugs 34 forming additional slots 35 which are adapted to engage and disengage projections 36 on the trays 29. Tension springs 37 with one end attached to a strap 31 and the other attached to the workholder 25 tend to rotate the straps 31 to the position shown at the left hand of Fig. I, in which position the trays 29 may be lifted from the work-holder 25. The straps are also provided with finger grips 38. By pressing the finger grips 38 together the straps wlll be rotated aganst the pressure of the springs 37 about the work-holder 25 and the tray projections 36 will be caught in the slots 35 as shown at the right-hand of Fig. H. The straps 31 when so moved are automatically locked by pins 39 on the spring pressed angle members 40, the pins 39 fitting in corresponding holes 41 in the work-holder 25. To release the straps 31 the angle members 40 are pressed against the springs 42 releasing the pins 39 from the holes 41 and permitting the tension springs 37 to return the straps 31 to their original position.

The work-holder 25 has an arm 43 affixed f; thereto by screws 44. The arm 43 is slotted at 45 and adapted to move with a reciprocatory motion about a pin 46 with a knurled knob 47 and lower threaded portion engaging the head of a screw 48. This screw 48 in turn fits in a threaded opening in the rim of the annulus 2. It may be turned to adjust the level of the surface upon which the arm 43 bears. By this adjustment and the further adjustment afforded by the threaded floating plate 20 turning within the disc 21, all the parts may be levelled and vertically aligned to compensate for a changein thickness of the grinding plate 1 or wear on the contacting surfaces of other moving parts.

Housed within the work-holder 25 is a brake mechanism comprising a brake rod 49 carrying a brake shoe 50 adapted to engage and disengage the floating disc 21. The brake rod 49 has a threaded end 51 fitting a correspondingly threaded opening in an arm 52 which is adapted to slide back and forth within the cavity 53. The brake shoe 50 is pivoted at 54 on the brake rod 49 and the shoe is normally held apart from the disc 21 by means of a spring 55 which forces the arm 52 outward until its shoulder 56 strikes a stop 57 on the work-holder 25.

It will be apparent from the description thus far that the rotary movement of the grinding plate 1 will cause a similar movement ofthe floating plate and disc 21 which will effect a rotation of the axis of p the work-holder 25. The work-holder being connected by the arm 43 to the annulus 2 will, of course, make one revolution for every revolution of the annulus", but its center will at the same timesmake five revolutions u about the center of the grinding plate 1, causing a reciprocatory movement of the arm 43 with five double strokes for each revolution of the annulus. During four doublestrokes of the arm 43, the brake arm 52 will not strike the rim of the annulus 2 on account of the 22 space between the grinding plate 1 and annulus 2 being sufficiently wide to permit the brake arm 52 to travel back and forth with the work-holder arm 43, but at one point in the operation of the machine (when the ele- 259 ments are in the position shown in the drawings), the space between the grinding plate.

1 and annulus 2 is so restricted that the brake arm 52 in passing will strike the annulus and be moved inward a short distance, thus applym the brake shoe 50 to the floating disc 21 for an instant. When the brake mechanism is operated the floating plate 20 and disc 21 will be restrained from rotating with the grinding plate 1, and will be subjected to the rotary movement of the annulus 2. Accordingly, the

axis of rotation of the work-holder will remain stationary for an instant with respect to the annulus 2. This will efiect a change in the angle a b 0 between a point on the grinding plate, the center of the grinding plate,

and the axis of rotation of the work-holder, which in turnwill eflect a change in the course which a point of the face of an article being ground will describe on the grinding plate.

To adjust the operation of the brake, I provide a set screw 58 so that the total length of the brake rod 49 and brake arm 52 may be varied and set at the desired measure.

The hub portion 59 of the work-holder 25,

except for the instant at which the brake is applied, rotates in the opposite direction from that of the disc 21. To provide a wearing surface on the disc 21 I form the disc with a raised portion 60 in the form of a circular 55 track eccentric to the disc 21 but concentric with the hub 59.

The operation of the machine will be apparent from the description of its constituent elements. If the brake mechanism were not employed, the path of each article of work would constitute a definite cycle distributed over the face of the grinding plate, but repeating itself. However, each time the annulus 2 completes a revolution, the application of the brake changes the angle between a point on. the grinding plate, the center of the grinding plate and theaxis of rotation of the work-holder, so that a new path or course is described. Theoretically a circle may be divided into an infinite number of degrees and fractions thereof so that the machine may be accurately described as operatupon a principle permittingthev Work to describe an infinite number of courses over the grinding plate. As a practical matter. thereis, of course, a limitation on the opera: tion without repetition (the period of application of the brake mechanism cannot be re duced beyond acertain point) but this limitation does not effect the practical operation ofmachines embodying my invention,because a repetition of the course described by a point on the work being ground, 1f it does occur, 1

will occur so infrequently that the grinding plate will wearuniformly throughout, this wear being distributed over its entire surface.

sitions of the axes-of work-holder and grinding. plate, resulting asit does in the uniform wearing of the surface of the grinding plate, renders it commercially practicable toincrease thecapacities' of machines of this type andaifords other advantages which will be manifest to those skilled in this art.

l/Vhile my invention has been described in some detail with respect to a specific embodiment thereof, it will, of course, be apparent that various changes maybe made in the particular form here illustrated and described without departing from the spiritof the invention, as claimed.

Having thus described my invention, I

claim:

1. A. surfacegrinding machine including a rotary grinding plate, a surrounding annu lus eccentric to said grinding plate. and

The automatic changing of the relative po- 7 adapted to begrotated in the oppositedirec-- eccentric to said grinding plate and adapted for oppositerotation, a floating plate frictionallyengaging said grinding plate, a bearing eccentrically mounted on said floating plate, a work-holder on said bearing adapted 1 to rotate with the said annulus, and means 1 whereby said floating plate is at times subected to the rotary movement of said grinding plate and at times subjected to the rotary movement of said annulus. 3. A surface grlnding machine including a rotary grinding plate, a surrounding annulus eccentric to said grinding plate and adapted for opposite rotation, a floating plate frictionally engaging said grinding plate, a bearing eccentrically mounted on said floating plate, a work-holder on said bearing and adapted to rotate with said annulus, and a brake adapted to engage intermittently said floating plate to subject the .same to the rotary movement of said annulus.

4. A surface grinding machine including a rotary grinding plate, a surrounding annulus eccentric to said grinding plate and adapted for opposite rotation, a floating plate frictionally engaging said grinding plate, a bearing eccentricaily mounted on said floating plate, a work-holder on said bearing adapted to rotate with said annulus, a brake normally separated from said floating plate, and a reciprocatory arm for causing said brake upon each revolution of the annulus to bear upon the said floating plate for an instant to subject the same to the rotary movement of said annulus.

5. A surface grinding machine including a rotary grinding plate, a surrounding annulus eccentric to said grinding plate and adapted for opposite rotation, a floating plate frictionally engaging said grinding plate, a bearing eccentrically mounted on said floating plate, a work-holder on said bearing adapted to rotate with said annulus, and means for adjusting the vertical position of said bearing with respect to said floating plate.

6. A surface grinding machine including a rotary grinding plate, a surrounding annulus eccentric to said grinding plate and adapted for opposite rotation, a pin on said annulus, a work-holder having a central bearing rotatingwith said grinding plate, the axis of said worloholder being eccentric to the axis of said grinding plate, and a slotted arm engaging the pin on said annulus whereby said work- .holder is adapted for relative reciprocatory and rotary movement with respect to said grinding plate.

7. A surface grinding machine comprising a carrier, a grinding plate rotatable with respect to said carrier, a work-holder eccentric to the grinding plate and engaged by said carrier, 21 worloholder support normally subject to the rotation of said grinding plate, and means periodically acting upon said work-holder support to connect said support with said carrier so that said support ceases to rotate with said grinding plate, thereby effecting a change in the relative positions of the axes of said grinding plate and work holder.

8. A surface grinding machine comprising a carrier, a grinding plate rotatable with respect to said carrier, a work-holder eccentric to the grinding plate and engaged by said carrier, a work-holder support normally sub-

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