US1171174A

US1171174A - Parabolic-mirror-grinding machine.

Info

Publication number: US1171174A
Application number: US86695214A
Authority: US
Inventors: Thomas Avery Corry
Original assignee: Individual
Current assignee: Individual
Priority date: 1914-10-16
Filing date: 1914-10-16
Publication date: 1916-02-08
Anticipated expiration: 1933-02-08

Description

T. A. CORRY.

PARABOLIQ MIRROR emuoma MACHINE.

A PfL ILC ATION FILED bar. 16. 1914,

Patented Feb. 8,1916.

3 SHEETS-SHEET 1.

.- IMIENTIOR WITNESSES 4 rrnn s'rarits rnrnn'r enrich THOMAS AVERY CURRY, OFIAREQUIPA, PERU.

IPARABOLIG-MIB-BOR-GRINDING MACHINE.

Specification of Letters Patent.

Application filed (ictobe'r 16, 1914. Serial No. 866,952.

To all whom it may concern Be it known that I, THOMAS A. Corny, a citizen of the United States, and a resident of Arequipa, Peru, have invented a new and Improved Parabolic-Mirror-Grinding Machine, of which the'following is a full, clear, and exact description.

This invention relates to machines or apparatus forthe manufacture and finishing of optical lenses or special forms of reflecting mirrors, and has particular reference to machines for concaving and polishing parabolic reflecting mirrors such as are used particularly 1n reflecting'telescopes, headlights, etc.

. Among the objects of the invention is to provide a device of a practical and reliable nature and which, when once adjusted, is adapted to operate practically automatically for the" purpose ofgrinding or concaving a piece of work-and which produces a concavity substantially parabolic within the practical range of the machine.

The'foregoing and other objects of the invention will hereinafter be more fully described and claimed and illustrated in the drawings forming a part of this specification in which like characters of reference indicate corresponding parts in all the views,

and in which- Figure 1 is a front elevation of a preferred embodiment of the machine, parts being in section; Fig. 2 is a side view of the same, also partly in section; Fig. 3 is a view corresponding, to the upper portion of Fig. 2 but indicating a modified form of counter balancing means for the grinding tool; Fig.

-4 is a modification of the lower portion of Fig. 1 indicating one preferred form of mechanism for manipulating the grinding instrument automatically, and Fig. '5 is a vertical section of the central part of Fig.

1 on a plane parallel to that of Fig. 1.

The several parts of the device may be made of any suitable materials, and the relative sizes and proportions, as well as the general design of the mechanism, may be varied to a considerable extent without departing from the spirit of the invention hereinafter more fully set forth and specifically claimed. I

Referring more particularly to the drawings, I show a main frame comprising prac-' ticall-y three legs or standards 10 having their feet connected at 11 to a base 12 adapted to besupported in any suitable manner in afsubstantially horizontal position. The

upper ends of the legs are secured to an annulus or collar 13 having an open center and. arranged in a substantially horizontal plane. The two side legs are arranged substantially diametrically opposite from each other and the other leg is arranged in the rear thereof,

Patented Feb. 8, 1916.

leaving the front of the machine free for the mounting and operation of the active portions thereof.

At 14 I show a vertical rotary tool shaft supported substantially centrally with respect to the annulus 13 within which the shaft is adapted to oscillate in a plane parallel to the vertical plane of the two side legs 10 and around an axis extending through the annulus 13 from front to rear.

The shaft 14 is journaled at its upperend in a clamp 15 and a sleeve l6projecting upwardly therefrom. The clamp is provided at the front and rear with a pair of arms 17 having cone bearing connections with a pair of adjustment screws 18 extending-hori-.

zontally through the annulus.

A suspension rod 19 is connected at its upper end to the clamp 15 and at its lower end is fitted loosely in a bearing block 20.

A block 21 is secured to the rod 19 aboveits.

lower end. The shaft 14 is journaled in the

blocks

20 and 21 but is free to slide verti cally within said blocks.

22 indicates a suitable grinding or polishing tool adjustably fitted to the lower end;

is journaled antifrictionally by means of collars 24 and 25' secured to the shaft and between which collars and the sleeve bearing balls are located. An arm 26 is secured to the sleeve 23 and projects laterall therefrom, the arm having a' surface 2 along its lower edge which is substantially perpendicular to the axis of the shaft. A. slide 27 bears upwardly against the'surface 26 of ';the arm and said slide is journaled upona' horizontal axis 28 extending between pairs of pantographie arms or toggle links 29' and 30, the pivot oraxis passing through selective holes formed in the links '29, whereby the relative lengths of the

links

29 and 30 may be varied. The upperends of the links 29 are pivoted at 31 to the clamp 21 and the lower ends of the lower links 30 are pivoted at 32 to the end of an arm 33 secured rigidly to and carried by a slide 34 movable preferably in a straight horizontal line along a 'bar 35 supported upon the side legs 10 and constituting what may be termed adirectrix. It will be .understood that the

toggle links

29 and 30, together with the slide 27, constitute the main support for the arm 26 and rotary shaft 14 and hence these elements constitute a stop limiting the downward movement of the shaft and the tool secured thereto.

The action of gravity upon the shaft 14 and parts carried thereby is counteracted to a greater or less extentby any suitable counterpoise devices. As shown in Fig. 1,

there is'e'mployed a coil spring 36 acting upwardly upon the shaft and supported upon the clamp 21. The effect of the spring is variable by virtue of'a winged nut 37 at the upper end of the spring. In Fig. 3, however, is shown another counterpoisedevice which comprises a weight pan '38 having a flexible connection 39 leading therefrom over direction pulleys 40 to a swivel 41. connected to the upper end of the shaft 14.

The adjustment of the effect of gravity upon the shaft and tool is necessary particularly in the finishing of a lens or mirror.

The slide 34 is adapted to be operated along the directrix by any suitable means, either by hand applied to a handle 42 or by means of mechanical devices such as shown in Fig. 4. In this figure is shown a cross head 43 slidable along guideways 44 extending horizontally and outwardly from one ofsary or advisable according to the diameter of the mirror or lens operated upon or in ac-' cordance with the amplitudeof movement of the tool 22. The axis 31 pertaining to 1 the upper pivots for the links 29 carried by the clamp 21 bearsa constant'relation to theaxis 17 around which the operating parts oscillate, and hence, as shown in Fig. 1, the

point 31 must swing in the arc of a true circle. The point 32 bearing a'constant fixed relation to .the slide 34 must move in a straight horizontal line or a line parallel to the directrix. It follows, therefore, that when the slide is'moved in either direction .the concavity is deepened or the curve from the normal or mid position shown in full lines in Fig. 1, the two

points

31 and 32 move apart. Since the

links

29 and 30 are pivoted together on the point or axis 28 and have their opposite ends pivoted to the

points

31 and 32, it follows that the point 28 is caused by the oscillation of the shaft to describe a curve of a character intermediate the straight line described by the point 32 and an arc of acircle described by the point 31. The slide 27 carried-by the axis 28 will therefore define or determine the path of movement of the tool 22 by reason of its cooperation with the arm 26 and sleeve 23 supporting the shaft 14.

With the parts arranged and proportioned substantially as indicated in Fig. 1, the path of movement of the active point of the abrading tool 22 is substantially a true parabola within the practical arc of oscillation, the focal center of the parabolic curve coinciding with the axis of oscillation of the shaft 14.' It is obvious, however, that the form of the curve may be variedby variously adjusting the relation between the several points indicated. For instance,bylowering the point 28, a flatter concavity will be produced, and by increasing the distance between the point of the tool and the point 32,

formed by the tool is sharpened.

The plate or job being treated and shown at 53 is supported in operation upon a turn- .table 54 secured to a spindle 55 preferably of conical form and journaled in a bearing 1 0 socket Said socket and parts carried therein are adjustable vertically by means of a set screw 5'? operating through the bottomof a casing or holder 58 shown .assecured to the central portion of the bed plate 12. The turntable may be caused to rotate at any desired speed and by any suitable means. I prefer, however, to rotate itcomparatively slowly by means of a worm 5900 operating with teeth 60 formed upon the periphery of the turntableand thereby constituting the turntable as a worm gear. The worm 59 is-shown as mounted upon a shaft 61 which is driven by miter gears 62 from a vertical power shaft 63 journaled in the mainframe of the machine. A main driving wheel 64 is secured to the shaft 63 and may be operated bymeans of a belt 65., To the upper end of the shaft 63 is secured a belt wheel 66 having a belt 67 leading there- 129 from to a'small pulley 68 journaled upon the aforesaid bearing sleeve 16. Pins 69 and 76 carried by the pulley and shaft 14 respectively serve to insure the rotation of the shaft from. the pulley while allowing a comparatively free slidable movement of the shaft. .1 The pin 70 is connected to a-collar '71 rigidly secured tothe upper end ofthe Qshaft. By virtue of the sleeve 16' the strain of the belt 67 upon the pulley is relieved from the shaft and hence all unnecessary friction between the shaft and its bearings 1s prevented.

Having thus described my invention, I claim as new and desire to secure by Letters Patent 1. In a machine of the character set forth, the combination of a support, a suspension member mounted upon a horizontal pivot in said support and adapted to oscillate around its pivot, a rotary shaft arranged in said suspension member and adapted to oscillate therewith, means to rotate the shaft, a tool carried by the free end of the shaft, and means cooperating with the suspension member and the rotary shaft serving to cause the active point of the tool to described a parabolic curve while the suspension member oscillates in the arc of a circle.

2. In a device of the character set forth, the combination of a rotary shaft, means to support the shaft for oscillation around a fixed axis but allowing theshaft to slide transversely of said axis, means to rotate the shaft in its support, a tool carried by the free end of the shaft, and means cooperat- I ing with the shaft and its supporting means serving to cause the point of the tool to describe a parabolic curve whose. focal center cfiiricides with'the axis of oscillation of the s a t.

3. In a machine of the character set forth, the combination of a main supporting frame including a horizontal annulus adjacent its top, a rotary shaft extending centrally of said annulus, means pivotally supporting the shaft on a fixed axis in said annulus and permitting the oscillation of the shaft around said axis, said shaft supporting means including a rigid member adapted to swing with the shaft in an arc of a circle,

a tool secured to the free end of the shaft, a rigid stationary member adjacent the plane of oscillation of the shaft, a slide movable to and fro on said stationary member along a path different from an arc of a circle, and means connected to said slide and cooperating with the shaft and its supporting means serving to cause the tool to describe a path having a form differing from both the path of theslide and an arc of a circle.

4. In a machine of the character set forth, the combination of a supporting frame ineluding a horizontal annulus, rotary shaft supporting member for the shaft including bearing arms journaled in a. horizontal axis in the annulus and including bearings in which the shaft rotates, every point of the rigid supporting member being adapted to oscillate in an arc of a circle around the pivotal axis of the shaft, a tool carried by the free end of the shaft and movable with the shaft longitudinally in its bearings, a rigid stationary member arranged transverse to the normal mid-position of the shaft, a slide fitted to the stationary member and movable to and fro thereon and describing a path differing from an arc of a circle, a pair of members pivoted together and having their opposite ends pivoted respectively to the rigid shaft supporting the said slide, and means cobperatmg with said pair of members and the shaft serving to cause the tool to describe a path differing both from that of the slide and an arc of a circle, substantially as set forth.

5. In a machine of the class set forth, the combination of a main support, a rotary shaft, means to support the shaft in themain-suppo'rt for-oscillation around a horizontal axis, said shaft support including bearing members in which the shaft is jou'rnaled and adapted to slide longitudinally, a tool carried by the free end of the shaft, a

rigid stationary member adjacent the path caused to describe a parabolic curve simultaneously with the operation of the shaft and support.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

. THOMAS AVERY COREY.

Witnesses:

G. G. STAFFORD, R. N. STAFFORD.