US2518501A

US2518501A - Adjustable crank means

Info

Publication number: US2518501A
Application number: US562010A
Authority: US
Inventors: Richard L Snyder
Original assignee: Individual
Current assignee: Individual
Priority date: 1944-11-04
Filing date: 1944-11-04
Publication date: 1950-08-15
Anticipated expiration: 1967-08-15

Description

Aug. 15, 1950 R. SNYDER ADJUSTABLE cmmx MEANS Filed Nov. 4, 1944 FIG. 1.

FIG. 3.

RICHARD L. SNYDER FIG. 2.

ATTORNEY Patented Aug. 15, 1950 UNITED STATES PATENT OFFICE (Granted under the act of March 3, 1883, as amended April 30, 1928; 3'70 0. G. 757) 3 Claims.

The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

This invention relates to improvements in lapping machines.

Due to the enormous demand created by the war for crystals of the piezoelectric type for frequency control purposes, mass production grinding methods have been developed. One important grinding or lapping machine has evolved from the drill press and is capable of simultaneously lapping a large number of crystals on both sides. Every effort has been made to perfect these machines to save time and materials and to simplif the lapping operation.

Such a machine is provided with two, spaced, horizontally disposed, lapping plates, one above the other. Loosely positioned between said plates is a crystal carrier which holds a plurality of crystals. A rotary motion is imparted to said crystal carrier by the spindle of the drill press which operates through a small crank and thereby moves the crystals between the lapping plates. 7 It has been found that such machines have the disadvantage of using the same crank for difierent sized crystals. In such operation, small crystals will not reach the inner and outer edges of the lapping surfaces and large crystals will go beyond said edges. An adjustable eccentric, small in size, simple to operate, requiring a minimum of machining and requiring a minimum of material (in view of the shortage of materials, tools and labor due to the war effort) is desired.

It is, therefore, an object of the present invention to provide an adjustable eccentric which is small in size and simple in operation.

It is another object to provide an adjustable eccentric which requires a minimum of material and machine work to manufacture.

It is a further object to provide an adjustable eccentric for a crystal lapping machine which will allow machines in present use to be efficiently used for lapping crystals of different sizes so that they may be adjusted to utilize the full lapping surfaces irrespective of crystal size.

It is a further object to provide an adjustable eccentric which is readily variable from zero to maximum eccentricity.

It is another object of this inventionto provide an adjustable crank arm wherein the depending pin at the outer end of the said arm may be readily replaced when worn, without requiring unnecessary labor and machining.

It is still another object to provide an adjustable crank arm which. may be adjusted without the likelihood of breakage of crystals or otherv parts. i v V In crystal grinding machines generally, under usual quantity production arrangements, the operator has access to the machineconvenientlyon1y from one direction which may be termed the front. crank will stop in various positions, and a large number of these possible positions are not convenient for access to the fastenings by which the crank elements are secured in their adjusted radius positions. The same is true of adjustment of holders and cranks for varying thicknesses of crystals. This is particularly true in the drill press machines, where the usual standard or post (springing from the drill press base and carrying the spindle and its drive)- will prevent the presentation of the hand or a tool from the rear or eiiectively from a wide range of angles toward the sides Where a bank of such machines is set up in close relation side by side, also, there is considerable risk of injury to the operator by the next machine if an attempt is made to present a tool from either side, as well as involving danger of disturbance of adjustments on the neighboring machine by impact of its parts against the arm or garments of the operator.

, On this account, it is an object of the invention to evolve a simple. and low cost device having the capabilities of adjustment required, of radius and height of an eccentric which will at the same time afford access to fastenings on the adjustment from opposite sides, so that if one such fastening is exposed toward the rear in such machines there will also be afforded access from the front to an equivalent fastening; andat the same time to keep these fastenings in the smallest,

tricity. As the auxiliaryv crank maybe locked at an position, intermediate thesetwo extremes,

any amount of eccentricity .therebetween may be readily obtained. I

The n vel ieatures which it is believed are In the stopping of the machine, the

posed .circulan bores 69,, I l

characteristic of this invention are set forth with particularity in the appended claims, but the invention itself will best be understood by reference to the embodiment set forth in the following description taken in connection with the accompanying drawings, in which:

Figure. 1 is a -perspec.tive view: of the lower 'portion of a crystal lapping machine embodying the present invention, wherein the adjustable eccentric is shown in its fully extended position, andpart of the upper lapping plate is cutaway for clarity;

Figure 2 is an enlarged perspectiveview of the adjustable eccentric of Figure 1,, wherein it is shown adjusted for relativelysm'a'll" eccentricity and Figure 3 is a vertical radial crosssectionalview of the said adjustable eccentric; wherein it is shown adjusted for maximum eccentricity.

The lapping machine; shown in the drawings, stands-uponabasal I, having-a fiat, horizontally disposed, top surface ['33 Resting upon said' sur face [3 is. a metal, disc-like, planiform lower lappingplate' I5, the'top, flat, horizontalsurface l1 of 'which forms the lower" lapping surface of" the machine: Positioned about the lower lapping plate I5 arefouraligning brackets l9, each of which issecure'dv to the base I I by' means of a machine screw 2'1.

Spaced above "the? lower lapping plate l5i's a metal annular upper lappingplat'e 23 of the same diameter, thelower,:flat, horizonta'lsurface' 25 of which f'o'rrns"v the; upper lapping' surface of the machine." The central portionof said upper lapping plate .23iscut' out'tb ifoi'ma circular aperture 21 concentric with" the plates outer periphery. Said: upper lappingplate 23 is also provided with two liftinghandles 29: Theoute'r periphery of said upper lapping plate 23' 'is pierced by four horizontally disposedfholes', into each of which is inserteda; spacerbar 51; The outerreduced ends of s'aid', spacer-bars 5F extend" respectively into vertical stS149, in the brackets 1'9, and they (and' consequentlyalso the plate'23i are'free to move vertically in" said" slots,

Interpos'ed between, the" two lapping, plates 23' are a plurality of" crystals 3| to be lapped. Said crystals 3| are .retainedin'spaced relationship relative to each otherlbya. carrier 33 which is.a dis'c ofinsul'ating, material} such as Bakelite,

.of. smaller diameter than the lapping plates 55, 23 (but of; substantiallygreaterdiameter than the aperture. 21),, an'd'piercedbya smallcircular axial hole 36 and a plurality of holes 35 shaped to loosely ,receive' the crystals" 3l. The carrier; 33

.is not as thick as the crystals..3l 'which are to be lapped." The machinenia'y'be provided with several carriers 33 ofdifierent thicknesses and having difierent sized'h'ole's" 35' s'o'that'a suitable .carrier maybe. used. in. lapping, crystalsof a particular thickness and size.

Axially positionedab'ove' the lapping plates I5,

Secured to the centric 39' fitted'with a" depending-wrist pin 4'! which i'sof'a size tomakea' rotatablefit inthe center hole -36 [ofith'e carrier .33.

The. adjustable eccentric". 39 comprises the upper-main...andlradial crank 38 and the lower auxiliary. and? variable-radius crank 40L The main'crank' 38"is pierced'bytwo vertically dis- The'iauxiliary crank 40 is similarly piercedby two vertically" di p s d.

circular bores l3, l5. Formed in the ends of the respective cranks at right angles to each of said bores 69, ll, l3, l5, and communicating respectively therewith, are horizontally disposed, threaded, set screw holes TI, 19, 8|, 83, each of which holes receives a set screw 85. The lower end of the. spindle 31 fits into the-bore 69. A single straight, circular knuckle pin 8'! fits into the apertures H, 73. A second straight, circular pin, which is the wrist pin 4! before mentioned, fits into the aperture 15 and extends downwardly beyond said aperture. Said spindle 31, and said pins 8T, M are held and locked in place by the four set screws aforesaid. It may be noted from Fig. 3 that pins 81 and H are of approximately the same diameter, so that assembly is corre- Spondingly simplified.

Inoperation of the lapping machine, shown in the drawings, the two lapping plates I5, 23 are disposed in register, the carrier 33 and the crystals' 31 being so positioned between the lapping plates i5, 23 that the crystals 3! will move over the full width ofthe lapping surface 25, but will not go beyond the edges thereof. The set screw 85 in the set screw hole 19 is then loosened and, while the auxiliary crank 48 is being supported in place manually, the spindle 31 is moved downwardly until the depending pin 4| is lowered into the center hole 36 of the carrier 33, through the central aperture 2'5. The said set screw 85 in the set screw hole 39 is then tightened. Rotation of the spindle 31 by means of the motor (not shown) will then cause'the crystals 3! to move about horizontally between the upper and lower lapping surfaces ll, 25, a suitable grinding compound being applied.

It is'readily seen that the parts of the adjustable eccentric just described' require a minimum of machining, that the eccentricity is readily adjustable and that any parts which may wear may be easily and inexpensivel replaced, such wear usually occurring mainly in the depending pin 4 l.

Although the embodiment herein described, to illustrate the present invention, is shown in connection with a crystal lapping machine. It will be understood that it is within the spirit of the invention to apply it to other lapping or grinding machines and to other uses.

What is claimed is:

1. In a crystal grinding machine of the character described, wherein a vertical spindle is operable over a bottom planiform grinding plate having an annular planiform grinding plate vertically free thereover, and wherein a' circular crystal carrier is free between the plates having avariable radius eccentric connection with said spindle;. an improved variable throw crank to connect the spindle and carrier comprising an upper crank arm constructed to be fixed to the spindle, a vertical bore therethrough adjacent its outer end, a knuckle pin slidable'therethrough, pinlocking means on the arm having an operating part exposed outwardly on the radius of the arm, a lower crank arm having a vertical bore therethrough adjacenteach end, either ofthe lastnamed. bores being capable of receiving slidably therethrough said pin, a wrist pin slidable alternatively in said holes of the lower crank arm to project therebelowand engage the carrier, and respective. pin-locking means at the. ends of the lower crank arm having, respective operating parts exposed longitudinallyon the ends of the arm and constructed for operation by a tool-while positioned approximately along, the longitudinal axis of the respective arm.

2. The structure of claim 1 wherein each said pin-locking means comprises an operating member set in the extremity of the respective arm accessible by a tool presented approximately in alignment with the longitudinal axis of the arm.

3. The structure of claim 1 wherein the said upper crank arm is vertically bored to receive the spindle slidably therethrough, and. a spindlebinding member thereon exposed radially opposite the outer end of the arm.

RICHARD L. SNYDER.

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

6 UNITED STATES PATENTS Number Number 10 348,286

, Name Date Wanzer Nov. 9, 1869 Crutchlow May 16, 1899 Siddle Sept. 8, 1925 Christiansen Sept. 10, 1940 FOREIGN PATENTS Country Date Italy May 15, 1937